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* Requires ZX-81.
Tested on U.S.
Version only.
SINCLAIR APPLICATIONS PRESENTS
ROM CARTRIDGES FOR THE ZX 8l.
ROM PACKS
e Eliminate the flustration of loading
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e 3 оп ROM character sets
e Program selectable
e Upper/lower case character set
e Graphics character set
e Math/electronics character set
e None of the above take up any
user RAM
e With 512 bytes of user RAM the
ROM PACK can build a Spanish
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О and é type characters
USER DEFINED
CHARACTER SETS
e As many as you have RAM for
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e Easy-to-use interface for defining
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e 10 Speeds
ON A 272 X 192
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324.95
Till October 15, 1982
$19.95!
6502 SOFTWARE
EMULATOR
e | earn 6502 machine language
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e User manual
e Plus introductory teaching guide
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e ‘‘Executes’’ 6502 machine code
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e Call Z-80 subroutines from your
6502 programs
e Limited 6502 Assembler
(Supports all 6502 mnemonics but
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STATE
e Graphic display of the 6502's
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e Single step, multiple break points,
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e "Fake" 1/0 and interrupts
3529-95
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e All features of the 6502 Software
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e Plus graphic display of the 6502
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User's manual for any of the
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Teaching guide for software and
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ZIP
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MAIL TO: SINCLAIR APPLICATIONS Norcross, GA 30093
(404) 921-4471
тн = ш вит чии та чия eee ee «ит «ит чип GRE «ит «ие өше «ит тыз еше еже «ше чыз «ша ена «ша өше еше сыш еме еже «ив «ии еше өне «ши GEM чи өше чие ею: чие сєз «иа сыш GER тше «на «на GEM сыз GEM өше Gum еше «но == GÀ
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ACTUAL SIZE 3 X2
e Fully built, tested and guaranteed. The use of this memory is as follows:-
Ф No additional power supply required. — 0 — 98K Sinclar ROM
@ Black plastic case no larger than 16K 8 — 16K RAM that is unaffected by
RAM PACK. NEW, LOAD, SAVE and can
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code routines.
16 — 32К BASIC Code, Display file,
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32 — 64K Variables
Ф No wobble problems
e Fully compatible with printer etc.
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including FREE ALIEN ATTACK (7K -M/code) — wale $11.00 (£5.75)
As reviewed in ‘Your Computer’ — (March 1982) the leading
U.K. Sinclair Publication. Almost 10.000 units sold in the U.K. so far.
PLEASE NOTE: All prices are fully inclusive and are applicable for export, including airmail postage. Payment may be made in sterling
(Money Order available at your bank) or your own U.S. $ cheque, made pavabie to JRS SOFTWARE.
Despatch normally 7 days from receipt of order
19 WAYSIDE AVENUE, WORTHING, SUSSEX. BN13 3JU Telephone: (0903) 65691
Explore the excellence of your ZX81 with a
> =
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ШІ
MEMOPAK ан memory extension for 179.95
Give your diminishing memory more byte.
MEMOPAK 64K RAM $179.95
The Sinclair ZX81 has revolutionized
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mands as 10 DIM A (9000). It plugs
directly into the back of ZX81 and does
not inhibit the use of the printer or other
add-on units. There is no need for an
additional power supply or leads.
Description of memory
0-8K ... Sinclair ROM
8-16K . . . This section of memory
switches in or out in 4K blocks to leave
space for memory mapping, holds its
contents during cassette loads, allows
communication between programs, and
can be used to run assembly language
routines.
16-32K ... This area can be used for
basic programs and assembly language
routines.
32-64K ... 32K of RAM memory for
basic variables and large arrays. With
the MEMOPAK 64K extension the ZX81
is transformed into a powerful com-
puter, suitable for business, leisure and
educationai use, at a fraction of the cost
of comparable systems.
Memory Extention Specialists
Memotech Corporation
7550 West Yale Ave., Suite 220
Denver, Colorado 80227
Ph.(303) 986-0016
MEMOPAK 16K RAM $59.95
With the addition of MEMOPAK 16K,
your ZX81 will have a full 16K of Di-
rectly Addressable RAM. It is neither
switched nor paged and enables you to
execute longer and more sophisticated
programs and to hold an extended data
base.
The 16K and 64K Memopaks come in
attractive, custom-designed and engi-
neered cases which fit snugly on to the
back of the ZX81 giving a firm connec-
tion.
Free service on your MEMOPAK
Within the first six months, should any-
thing go wrong with your MEMOPAK,
return it to us and we will repair or
replace it free of charge.
Try MEMOPAK with no obligation
You can use our MEMOPAK in your
home without obligation. After 10 days
if you are not completely satisfied,
simply return it for a full refund.
Coming soon .....
A complete range of ZX81 plug-in
peripherals:
MEMOTECH Hi-Res Graphics
MEMOTECH Digitising Tablets
RS232 Interface
Centronic Interface and
Software Drivers
All these products are designed to fit
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Further information forthcoming.
Yes! | would like to try the Memopak. | understand that if I'm not complete satisfied,
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| О Check
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Lost 1 ee c
The magazine for Sinclair users
Ei Ги
July/August 1982 Volume 2, Number 4
DEPARTMENTS PROGRAMMING TECHNIQUES
4 р ЗА LORD EE. iM ае M 64 DEF опе Ха ас Passler
Translating other Basics
10 BYNC МО. Grosjean
68 Handling Strings from Another DiMension ...Berggren
1 2 OP TINS o oL tg ALES DO AS Berggren, Rainwater ZX80 abilities; game
1 4 Just for Ғип................. Boynton, Bush, Grosjean SYNC IN OUTER SPACE
1 6 о > hak ur О огиз Ornstein 48 ZX Понос Fowkes
The 2Х81 Parser (Part 2) Alien attack in a fast action Basic and MC game
22 Kitchen SYNC .............. Groupe, Tardiff, Zatkovich 60 Galaxy Іпуадегѕ .............................. Gervais
Two to the What? Reflex challenge from outer space
74 Hardware Tips ........ Dowell, Hartung, Hornung, Ingle 61 Mioto НИНАНЫ ы... с И Smith
Ear Input Circuit, Top Line Hook, Power Filtering, Strong
KBD Signals, ROM Changing, Memory Expansion Power,
Thick Black Bars
78 НАИ О ТОИ АЕ Ир А ee E
80 Index to Advertisers .................................
HARDWARE
38 Double Your Memory ......................Schneider
Small aliens; small ships
62 Comet GrusMar оо... ы УТО Dawson
Smash a fragment; save a city
63 Crossing the Asteroid Belt ................... Hampson
Dodge the asteroids
72 Alien Treasure .............................. Chandler
Gather before the alien monster gets you
ZX81 internal RAM upgrade REVIEWS
28 Understanding Your ZX81 ROM ............... Keeney
MATH Book review
43 Understanding Floating Point Arithmetic......... Logan 30 Sinclair ZX Spectrum ......................... Tebbutt
Part 3 Hardware review
Volume 2, Number 4
Staff SYNC (USPS: 585-490: ISSN: 0279-5701) is published bi-
BEL АР РР 55. И A RR се; Paul Grosjean monthly by Ahl Computing, Inc., a subsidiary of Ziff-Davis Pub-
Reta fal E DECIES od COE David Ornstein lishing Company. David Ahl, President; Elizabeth B. Staples, Vice
UE Correspondent. соло шу уш Yl Martin Wren-Hilton President; Selwyn Taubman, Treasurer; Bertram A. Abrams, Sec-
сазы По а a RS д үз Б eee ENG Elizabeth Magin retary. 39 East Hanover Avenue, Morris Plains, NJ 07950. Second
ais doll 1 а ye Pe Susan Gendzwil class postage paid at New York, NY 10001 and at additional mail-
Assistant Art Director...........................Diana Negri Rudio ing offices.
ZO DT tok LR sts чыз, хр Karen Brown Subscription rates: USA: One year (6 issues), $16; Two years (12
Rena Cole issues), $30; Three years (18 issues), $42. Canada: $3 per year
Financial Coordinator... ща William L. Baumann additional. Other foreign: $5 per year additional.
Pemounetand Finance.) ооо ин Patricia Kennelly For SYNC advertising information, contact Jim Beloff, SYNC Advertis-
ca Oh ET ERR UC OPEP SERO CS Francis Miskovich ing Sales Manager, Ziff-Davis Publishing Company, One Park Ave., New
Carol Vita | York. NY 10016 (phone 212/725-4216).
Alverdsne Sales Малаге О e a E N, Jim Beloff All other correspondence should be addressed to: SYNC, 39 E. Hanover
MEMBER
Ave., Morris Plains, NJ 07950. In U.K., SYNC, 27 Andrew Close, Stoke
Golding, Nuneaton CV136EL.
Postmaster: Send address changes to SYNC, PO Box 789-M, Morristown,
NJ 07960.
Photos from Star Trek П: The Wrath of Khan courtesy of Bruce Birmelin/Paramount Pictures.
July/August 1982
letters
LSCROLL
Dear Editor:
For entering machine code routines like
LSCROLL (SYNC 2:2) it is helpful to use
the 8K КОМ string concatenation abili-
ties. The procedure involves breaking up
the one long string in line 10 into a series
of shorter strings which are entered line
by line.
Set the lines up as follows:
10 LET D$=“(begin entering mc num-
bers)"
20 LET D$—D$- "(continue entry)"
30 LET D$—D$- "(continue entry)"
etc.
Thus each new line includes all the
preceding lines, and we end up with the
whole string from the short strings. This
makes it much easier to correct the
entries since each line can be individually
EDITed.
= Also, the following lines give several
advantages in SAVEing:
1 GOTO 3
2 SAVE "name of program"
You now do not have to type in SAVE
every time when you want to make sev-
eral SAVEs. Simply type in GOTO 2.
The program will SAVE itself, then RUN
itself. If you want to make more than one
SAVE, you must change the last character
of the name of the program to normal
video from inverse (for some reason, the
system does that).
The real advantage comes when
LOADing because the program will now
start itself!
I have two other hints. DATA state-
ments could be simulated using strings;
the 8K’s VAL function could be used to
remove VALues. It usually makes enter-
ing MC easier to show a zero as 0 with a /
through it.
Erik Sawyer
1213 Patriot Dr.
Slidell, LA 70458
4
Dear Editor:
Douglass Sharp’s LSCROLL program
(SYNC 2:2) is a very useful expansion of
the ZX81’s graphics capabilities. As writ-
ten it requires the 16K RAM, but a few
modifications allow LSCROLL to perform
its magic with the 2K RAM since it
occupies only 172 bytes. (The numbers
correspond to the steps in the original
article.)
1) Rather than have D$ take up val-
uable space within the LSCROLL рго-
gram, enter D$ first without a line number
as follows:
LET D$-
LET
LES
LET
LET
LET
LET
LET
LET
LIT
СЕТ
LET D$=D$+" ЗОООО"
These lines һауе the same length as
those in Figure 1 in LSCROLL, but the
entries have been changed to conform to
the addresses appropriate to the 2K RAM.
Furthermore, the arrangement makes
checking the entries easier.
Enter lines 4 and 20-80 as in Figure 1
but change the address in line 50 to 18259.
Then add:
10 CLS
90 STOP
100 SAVE “LSCROLL”
110 PRINT “GOTO 4 (TO RUN)"
2) SAVE by entering GOTO 100
(NEVER use RUN with this program for
it will erase D$).
3) Enter NEW.
4) Enter POKE 16388,84 and POKE
16389,71. Enter NEW.
5) LOAD “LSCROLL” and then enter
D$=D$+" 600ED427D32
"ЗАРЕ47ЕЕ160861475Е0"
D$-D$-"OSZFE47368FF47D600C607147FE15D2714"
D$-D$-'"70376473E1632FF47FS36FF4747F136F"
D$-D£$-"EA780FE16DA954726002E1638FE474FO"
FF47EDSRBOCAOOEFFFS3SAF "
D$=D$+" E476FF 1260006001 AF E7SCAAF 47 1 3C3A"
D$=D$+" S470CA7ESED42E 1 CABC47 13030547060 "
D$-D£$-"OFS3SAFFA7AFF1CSDSE1237EFE76C2C74"
D$=D$+" 7E5G47EDS522R7D4DD6OOE1C2EO47ESDI1C "
D$=D$+" 3F54723DC2E847 13C3F 1470600081 3D5E"
D$=D$+" 1SSEDROSZEOOLSLECIOBR79DS600C2C447C "
GOTO 4 (as the screen reminder indi-
cates). In a few seconds the number 21093
will appear. If it does not, check for an
error in D$.
To execute, use RAND USR 18260. To
change the values of XX, YY, and CC
(Figure 3), POKE the appropriate values
into 18430, 18431, and 18418 respec-
tively.
Figure 5 should be corrected as fol-
lows:
7F66 with 32614, not 32615
7F95, not 7ЕА5, with 32661
7FB4, not 7FC4, with 32692
7ЕЕ5 with 32741, not 32740
Harold Miller
Mountainview
Route 3
Clarkesville, GA 30523
SYNC Magazine
Software Breakthrough!
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3) Loads of Fun 7) ZX80 and ZX81 compatable
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THE INNOVATORS
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Visit our Showroom 10:00 - 6:00 Monday thru Saturday
PRIUS: MICROCOMPUTERS PLUS, INC.
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PHONE: (309) 342-9572
Card
Welcome
Flag Use
Dear Editor:
I just saw a copy of SYNC 2:1 with
Philip Gervais's tip on flag use:
100 LET A—ABS(A-1)
A simpler and shorter statement to do the
same thing is
100 LET A—1-A
Keep up the good work; I enjoy the
magazine.
David Schultz
Total Information Services, Inc.
PO Box 921
Los Alamos, NM 87544
Dear Editor:
An easier way to change a flag is
LET A=NOT A
This is also 10 bytes shorter.
Tim Goldingham
11 Furze Platt Rd.
Maidenhead SL6 7ND
United Kingdom
PREMIUM DATA CASSETTES
*MANUFACTURERS WHOLESALE PRICES*
LENGTH
C-10 59
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C-60 .89
C-90 $1.29
SOFTWARE PUBLISHERS —LET ACTS AUDIO
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(305) 423-0338
1 CASSETTE 100-PACK
Key and Token
Expressions
Dear Editor:
As Richard W. McDaniel points out
(SYNC 1:6), the use of key and token
expressions in PRINT and REM state-
ments can save typing time and memory.
There is, however, another way to insert
these into a program which is sometimes
easier.
Entering THEN gets the ZX80 and
ZX81 into condition to accept keystrokes
as tokens. Suppose that you want to
define A$ as "STOP SEEING YOUR
NAME IN PRINT FOR THE NEW
YEAR". You would key it in as follows:
10 LET А$=“ТНЕМ STOP (delete
THEN) SEEING YOUR NAME IN
THEN PRINT (delete THEN) THEN
FOR (delete THEN) THE THEN NEW
(delete THEN) YEAR"
This is easier than it looks. The
"DELETE THEN" procedure uses only
three keystrokes: backspace (shifted 5),
delete (shifted 0) and forward space
(shifted 8).
Basil Wentworth
1413 Elliston Dr.
Bloomington, IN 47401
SALES FILE:
500-PACK
CHECKING:
Lists up to 30 deposits showing amount of deposit and date entered.
Lists up to 100 checks and displays check number, date and to whom check was
written.
Lists by account the total of the checks written to any given account. Keeps a
MAILING LIST:
number quickly.
Lists all names.
INVENTORY (1):
thert.***
INVENTORY (2):
Changes or deletes.
***Christmas cards are a snap with this program.***
Hams and the ZX81
Dear Editor:
I am a delighted ZX81 owner. I am
also an amateur radio operator (ham).
Rather than trying to communicate
with other ZX81 owners by newsletters, I
would be interested in comparing notes
more directly: I propose to organize a
ZX81 network on radio. This would entail
deciding on the frequency, day of the
week, and time of day. After this we
would conduct our regular communica-
tions on a conversational basis.
Other combination radio amateur oper-
ators and Z X81 users are asked to contact
me so that we can get organized soon.
And, if you have a “ham” on the SYNC
staff, it would be wonderful if he would
meet with us on the air to field some of
the questions which are sure to arise!
Dean Sturm, KSCYW
1823 Enslow Blvd.
Huntington, WV 25701
Ed. — We do not have a "ham" on our
staff, but we have heard from some
operators interested in combining these
two interests. One ZX81 Ham network is
already organized and publishes a news-
letter QZ X (contact Martin Irons, K2MI,
46 Magic Circle Dr., Goshen, NY 10924,
for details). We would appreciate hearing
of any others.
LET YOUR ZX80 8K ROM - ZX81 WORK FOR YOU.
ALL PROGRAMS:
On cassette, Require 16K Ram, Are menu driven and
Automatically save on tape.
Will hold up to 125 products with their wholesale and retail prices.
Separates and totals wholesale and retail prices and shows the amount of profit in
up to 25 different accounts.
Records inventory automatically or may be changed manually.
Keeps a running total of sales tax.
Has a cash register mode which will identify, total and add sales tax while it
automatically does your bookkeeping.
***A must for any small business.***
$19.95
running total of checks written and the balance left in your account.
***Great for tax records.***
$9.95
Holds up to 100 names, addresses and telephone numbers.
Search by name, city, zip code, or phone number to find any address or phone
$9.95
May be used for everything from keeping an accurate inventory for your business
to your personal record collection.
Holds up to 150 items with comments for each.
Comments may be used for serial numbers, dates, prices or location.
List all items, search for a single item, change or delete any item.
***Every one should have an inventory of household items in case of fire or
$9.
9.95
Same as above without comments.
***Holds 300 items.***
Three $9.95 programs for $24.95
Add $1.00 per tape shipping.
Send certified check or money order to:
HEATH COMPUTER SERVICES
950 EAST 52 SOUT
GREENTOWN, IN 46936
$9.95
SYNC Magazine
gw
For the first time —
AVAILABLE
IN THEUSA!
4 NEW Handbooks for
your Sinclair ZX-81 or
Timex-Sinclair 1000!
AS, ии ХАЖ ХА АЯ 4 ии ЖҰ А 44 А 4 А4 А4 ҰЯ 4« А ии ии ии кая я иж ж Ұя
MASTERING MACHINE CODE
ON YOUR ZX-81
by Toni Baker
Until this comprehensive, yet easy-to-understand, handbook, there
was virtually no material available about the ZX machine code.
Using this guide you'll learn the ins and outs of ZX machine code
translation. Discover the secrets of the ZX-81, and even see how to
adapt the code to the ZX-80 machine. When you understand the
language translations between BASIC and the ZX machine code,
you'll enjoy the workings of your computer to the utmost!
49 EXPLODING GAMES FOR THE ZX-81
Edited by Time Hartnell
Galactic Intruders, Breakout, Checkers, Death Maze, Star Trek,
Smugglers Mold, and forty-three other favorites are all here, newly
adapted especially for you and your new ZX-81 personal computer.
This fascinating gamebook gives you programming instructions for
all 49 marvelous games PLUS complete and easy-to-understand
game rules. This wonderfully exciting hardcover playbook can be
ОҢ a ши
LIA A B Жж Ж 4 ааа я а а ка а 000330 47!
@eseee eee
оооооооооооооооооооооооооооооооооооооооооооооооооооое во
MAKING THE MOST OF YOUR ZX-81
by Tim Hartnell
All new for you and your new ZX-81, this handbook focuses on the
additional features of the ZX-81. You'll have new games and use-
ful learning tricks, and you'll also see how to write programs that
really work. It will guide you through start to finish, using each
feature and function of your new ZX-81 personal home computer.
THE ZX-81 POCKETBOOK
by Trevor Toms
This handy new programming manual really gets you into ZX-81
functions. Don t just type someone else's programs. . . now you сап
create your own and understand why they work. It's fun to learn all
about computing with the ZX-81 POCKET BOOK as a guide.
You'll see what your new ZX-81 can do, and what extras will make
‚ see how to use ZX-81 BASIC in the best
. learn to avoid frustration and retyping with program and
it able to do even more. .
ways..
data file storage and retrieval techniques—and for ZX-80 owners,
you'll learn how to convert your ZX-80 to the advanced ZX-81
capabilities. And there's so much more! This road map to the ZX-
81 can be yours—it's "or every penny
* & * A OO UU UU ж ж ж X
*
* Üsing hee Brake vod Т ЕЕ amazed at how fast you'll become a ZX-81 wizard. Of course, buoni don t find he books helpful and inter-
esting return them within 15 days for a full refund, and owe nothing.
ххх
RESTON PUBLISHING COMPANY с/о
Mail to:
PRENTICE-HALL INC., Book Distribution Center
Route 59 at Brook Hill Drive, West Nyack, New York 10995
Please send me my 15-day trial copies of the following titles:
MASTERING MACHINE CODE ON YOURZX-81, by Toni Baker, (R4262-3), $18.95
- 49 EXPLOSIVE GAMES FOR THE ZX-81, by Tim Hartnell, (R2087-6), $16.95
- | MAKING THE MOST OF YOUR ZX-81, by Tim Hartnell, (RA189-8), $16.95
— ТНЕ ZX-81 POCKET BOOK, by Trevor Toms, (R9525-8), $16.95
Name
Address
City
| VISA O
account #
signatur
expiration date
Now you can charge your orders! Just fill in the information below:
[1 MASTERCHARGE
Save! If check or money order, plus your state's sales tax, accompanies your order, publisher pays all postage and handling charges. Same money back guarantee applies.
Dept. V
V-0852-W7-(3)
ZX80 ROMs
Dear Editor:
In Michael Rubesch's “4K/8K ROMs
in One ZX80" (SYNC 2:2) the reference
to "pin 28" of the modules rather than to
"pin 28" of the IC socket was a bit
confusing. Later PC boards do have a 28-
pin socket for the ROM while the ROMs
have only 24 pins. Also I have found that
the earlier ZX80 boards have only 24-pin
sockets if they have sockets at all. The
power pin then is pin 24 of the ROM
module which must be inserted at pin 28
of the later sockets.
Robert D. Hartung
PO Box 125
Palmyra, NY 14522
Hardware Suggestion
Dear Editor:
In this avalanche of new hardware for
the ZX81 I wonder how many manufact-
urers realize that many of us bought the
ZX81 because it is small. I can put it and
my equally small cassette recorder intoa “| TSGT Chuck Taylor
thin slipcase and use it anywhere а TV is | Diyarbakir
available. No other low or medium priced Turkey "ы
machine offers that degree of portability.
Every manufacturer of hardware for the
ZX81 should keep this in mind and should
include the size of the product in ads. I
favor stuffing as much memory and other
extensions inside the case as possible.
Harold Miller
Mountainview
Rt. 3
Clarkesville, GA 30523
Inventory
Dear Editor:
The /nventory program (SYNC 1:6)
was both enjoyable and useful. Here is an
improvement to SAVE the program (and
variables) as directed by the prompt in
line 2018:
Change line 2020 to:
2020 IF S$—"C" THEN SAVE
“INVENTORY”
Add:
2019 INPUT S$
2021 STOP
Thanks for a great magazine!
Bruce Birmelin/Paramount Pictures.
OMNI TEMPLATE
FOR ZX-80 and ZX-81
WHAT IS OMNI TEMPLATE?
Itisa template program for generating other programs.
EXTEND YOUR ZX81 SYSTEM While developing programs, our staff needed a collec-
| tion of general utilities to avoid the burden of repeating
m - - TEES T the same routines over and over. This gave birth to
Modify. спо Sinclair firmware OMNI TEMPLATE. We found it so effective that we
decided to share it with others.
WHY SHOULD YOU HAVE IT?
Itisa great training tool. It helps you to develop a habit
of writing professional-looking programs rather than
rag-tag patch works. It makes programming fun.
WHAT DO YOU GET?
You will receive a cassette tape of OMNI TEMPLATE
Program prerecorded and ready to use. Three addition-
al programs: RACING, INDEX-CARDS and FIT-
POINTS, which were developed Бу OMNI TEMPLATE,
are on the tape in addition to OMNI TEMPLATE. A
add memory that won't forget! !
O Add your own system utilities
о Install permanent machine language
subroutines
п Up to 8K nonvolatile memory
п Use 6116 RAM or 2716/2732 EPROM's
п Compatible with 16K RAM packs
COMPLETE KIT:
Plated-through, masked, & silkscreened
pc board; all components, sockets, and
connectors; supplied with a 2K 6116P-3
CMOS RAM (board will accept up to 8K).
Bare board $15 post paid. Check/money
order (MI residents add 45) То:
HUNTER 1630 Forest Hills Dr. Okemos
Michigan 48864
520595 Please include $1:95 H
Shipping & handling
complete listing of OMNI TEMPLATE and a well-
documented manual describing how to use OMNI
TEMPLATE is included.
HOW DO YOU GET OMNI TEMPLATE?
It is $9.50, if ordered before September 1, 1982. It
becomes $14.50 after that. Please add $1.00 for shipping
and handling. Send money order or check to:
Omni Technology
P.O. Box 10630
Pittsburgh, Pa 15235
PA resident please add 57 cents for PA sales tax.
KAYDE Electronic Systems
ZX80/1 $75.99
ZX KEYBOARD WITH
REPEAT KEY
Fully cased keyboard ........ $75.90
Uncased keyboard....... ..... $55.90
Keyboard Case................... $21.90
This is a highly professional keyboard using executive buttons as found on top quality
computers. It has a repeat key and comes complete in its own luxury case. This is a
genuine professional keyboard and should not be confused with toy keyboards currently
available on the market
KAYDE 16K RAM PACKS
The 16K RAMPACK simply plugs straight into the user port at the rear of your computer. It is fully
compatible with all accessories and needs no extra power and therefore it will run quite happily on your $59
Sinclair power supply. It does not over-heat and will not lose memory at all. As you may know. some .90
makes go down to 11K after being on for a while.
This 16K RAMPACK is very stable and will not wobble or cause you to lose your programme It comes
fully built and tested with a complete money-back Guarantee.
KAYDE FLEXIBLE RIBBON CONNECTOR
Stops movement of RAM PACK and other accessories
(Not needed with a KAYDE RAMPACK)
KAYDE 4K GRAPHICS BOARD
The KAYDE Graphics Board is probably our best accessory yet. It fits neatly inside your 2Х81. It
comes complete with a pre-programmed 2K Graphics ROM. This will give nearly 450 extra graphics
and with the inverse makes a total of over nine hundred.
The KAYDE Graphics Board has facilities for either 2K of RAM (for user definable graphics). 4K of ROM d
or our 4K Tool Kit Chips that will be available shortly. All the graphics are completely software
controlled, therefore they can be written into your programmes. Here are a few examples A full set of
space invaders — Puckman — Bullets, Bombs — Tanks — Laser Bases and Alien Ships.
NO EXTRA POWER NEEDED
KAYDE 16K GRAPHICS BOARD SOFTWARE
РЕСКМАҺМ: The only true ZX version of the popular arcade game. $
Centipede: “Іп а! | think this is the best presented moving graphics program lve yet seen. Phil Garratt. 7 1 9
Interface. 0
SPACE INVADERS: Тһе best version available anywhere. Graphics software can only be used with a graphics board
Centipede: "па! | think this 15 the best presented moving graphics program Гуе yet seen." Phil Garratt, $7 7 9
Interface. т
3D/3D Labyrinth: А Cubit Maze that has corridors which may go left, right, ир, down. Peckman (the 0
latest addition іп 81 games).
Е К BAMPACHE $59.90 saen i
Poat o. pèn Sy | Please send me... 2: ЭК graphice boards $59.90 each |
Kayde Electronic Systems Ltd | Please send me...................... 16K graphics board software $11.90 each |
y Please send me ............................................. 16K 81 software $11.90 each ,
The Conge [буын now
Great Yarmouth + мыш |
Norfolk NR30 1PJ ENGLAND d қ
Tel: 0493 57867 (Dept. 5Ү1) i ess |
|
Please pay by ; |
International money order or certified
cheque for immediate delivery. à Please add $5 p&p for all hardware and $2 for all software. Please make :
cheques payable to Kayde Electronic Systems Ltd.
PEE eue e ei] (ue ares cap mes mim ме сей жеде ке жада a Й
Sync газета
Paul Grosjean
SYNC in Outer Space
Space games lead the list of the games
that SYNC receives. This we would
expect since shoot-the-aliens games have
become standard fare in the computer
game field.
Certainly the computer is ideal for
playing such games. As we have seen in
recent years, modern instruments of war
depend heavily upon computer controlled
technology. Hitting the target used to be
the result of an almost intuitive interpre-
tation of a host of variables which was
then put into action by eye/muscle coor-
dination. The most important factor in
hitting the target seemed to be luck —
another name for the unknown or inmea-
sureable variables. The lack of instru-
ments to measure and calculate led to the
use of massive fire power in the hope that
something would hit the target even-
tually.
Now, however, hitting the target is a
matter of computation based on precise
measurement with lasers or radar. Since
FOR YOUR
space warfare involves speeds, distances,
power, and logistics beyond our exper-
ience, it is necessarily computer warfare.
While the technology was developing
that made space warfare possible, our
imaginations were also being prepared.
Science fiction writers such as E. E.
Smith, A. E. van Vogt, and Isaac Asimov
prepared us to think of conflict between
humans and aliens and between humans
and humans on a galactic scale.
Movie features and serials provided our
imaginations with the visual and sound
effects. The famed radio broadcast of H.
С. Wells s War of the Worlds in 1938
raised conflict with the aliens high in the
national consciousness. Finally TV put
space into every living room. The old
movies were shown again, the new movies
reached larger audiences, and programs
were developed around science fiction
themes, most notably Star Trek. A space
vocabulary has developed and become
part of our daily vocabulary.
We have the building blocks for story
telling, and the computer has become the
means of telling the story, but now the
player participates in unfolding the story.
LET A-(something) is necessary to the
computer, but to the player LET A may
really equal a space ship, an alien, a
minefield, a forest, a castle, a maze—
whatever the imagination desires. A given
computer program can provide a host of
stories without changing a line in it. We
only need to change the terms we assign
to the variables and the relationships we
have instructed the computer to work
out.
In order to simulate some of the un-
knowns of real life, we even introduce
random numbers and elements into the
program. SYNC receives from time to
time games that are purely the "battle of
the random numbers." In general, unless
the program illustrates some significant
programming techniques, these are
rejected because the player's skill and
judgment are vital parts of any satisfying
game. If the player wins, he can claim the
victory for his skill or ability; of course, if
he loses, he can still blame bad luck.
In this issue we have gathered some of
these games into a theme section "SYNC
in Outer Space." We are grateful to
Paramount Pictures for providing photos
from Star Trek II to highlight our theme.
"n
COSMONICS
ZX81 HARDWARE/SOFTWARE EXTENTIONS
CS 17 Cassette Read/Write Utilities. Allows the user to
selectively read & write strings and arrays to a cassette,
which can be used by the same program or a different pro-
ZX-81/TIMEX 1000
*KEYBOARD BLEEPER—Provides audible feed-
back, improves your keyboard cheaply, fits in-
side. All simple plug-in connections. No Solder-
ing Required. Aids faster more accurate pro-
gramming. All normal and shifted keys bleep in
slow and fast modes. (All 210 characters)
$19.00 includes instructions and postage/hand-
ling.
"LOADING AlD—Removes guesswork from ad-
cassette
CS 21 Software for TTL Serial Output Port. Provides cor-
rect RS232 timing; provides Sinclair character set transla-
tion to ASCII.
CS 21 cassette ;
"СН 21 Complete Plans for 2 | С Serial Output Port for ZX81.
CH 21 plans
"СН 21K 2 IC Serial Ouput Port Kit for ZX81 (complete
plans and parts)
CS 22 Software for Serial Input. Provides RS232 input tim-
ing and provides ASCII to Sinclair character translation.
cassette
*CH 22 Complete Plans for ZX81 Serial Imput Port.
justing cassette recorder volume. Optimum level
attained when red and green L.E.D.'s flash in
unison. between and
recorder.
$21.00 includes instructions and Розева
ling.
*T-SHIRTS—Black with red lettering "Sinclair
2Х81”. State size required, 24" — 44".
57.00 includes postage/handling.
FULCRUM PRODUCTS, DEPT. U
HILLSIDE STEEP LANE
FINDON, W. SUSSEX, ENGLAND
BN14 OUF
Plugs-in computer
СН 24 Complete Plans for В5232<-> TTL Level Converter.
CH 24 3
CH 46 46 pin edge connector for ZX81.
connector
All cassette software listed here requires a minimum
of 2K RAM
*Note: Any modification made on the ZX81 may
invalidate the Sinclair warranty.
Please add $1.50 postage and handling with each
order.
California residents add 6% sales tax.
COSMONICS, Box 10358, San Jose, CA. 95157
SYNC Magazine
WANT TO FIX YOUR SINCLAIR? ADD MORE MEMORY? ADD A BUSS? WE GOT YOUR PARTS.
We "eld all the parts you need to repair your Sinclair with the ео of the Sinclair Logic Unit, the ROM,
and the Printed Circuit Board. In addition we carry OK. WELLER. and XCELITE tools, HAMMÓND, and PAC-TEC
cases and VECTOR breadboarding and prototyping supplies. We stock resistors, capacitors, integrated circuits,
descrete solid state devices, switches, sockets, connectors etc. etc. Below is a very small sampling of our products.
If you see what you need give us a call, if you don't write for our free catalog.
INTEGRATED CIRCUITS FULL-SIZE KEYBOARD
INCREASE YOUR COMPUTING
VOLTAGE REGULATORS
TIME BY DECREASING TYPING TIME
POSITIVE NEGATIVE
ADD A FULL-SIZE KEYBOARD TO YOUR
ZX-80/81 OR MICROACE. YOUR FINGERS
E 0 7805 45V 7905 -5V
тата 442°. 1042. 42
WILL LOVE YOU FOR IT.
GS Ц 7815 +15 9194-15
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SINCLAIR ÁE 5
CONNECTOR | MODULATOR
GOLD CONTACTS
WIRE WRAP OR
SOLDER TAIL
$7.50
td
USA VHF 5.95
DATA
CASSETTES
5175
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by Maxell
90 тіп with case
№ М
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LM323K 5VOLT
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OUR KEYBOARD HAS 62 KEYS SO YOU CAN
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AND RESET. EACH KEY HAS GOLD CONTACTS
TUE ЫШ я AND IS FIRMLY MOUNTED TO А BLACK METAL
Дара а di з PLATE WHICH MEASURES 15-1/2" BY 4" AND
Te PF 5 DOUBLES AS AN ATTRACTIVE FACE PLATE.
BEST OF ALL YOU CAN GET YOURS IN KIT
MEMORY FORM, COMPLETE WITH INSTRUCTIONS, OR
WIRED AND READY TO GO. EITHER WAY WE
2114 1KX4 STATIC 4.00 8/28.00 WILL INCLUDE THE EXSPANSION PLANS.
4118 1KX8 STATIC 8.25 8/58.00
6116 2KX8 STATIC 14.95 8/125.00
KEYBOARD КИТ. 34.95 WIRED & TESTED..49.95
4116 16K X1 DYNAM 3.50 8/24 00
2716 2K X8 EPROM 12.00 8/84.00
2732 4KX8 EPROM 19.95 8/135 00
TTL
+ + © © © © o
5 screw high strength shell
JOYSTICK
4 - 10K Linear pots
1- V2 metal handle
2- V8 square
$5.95
IC SOCKETS
*PIN SOL WW
YOUR
ULTIMATE POWER SUPPLY
WHY WASTE TIME BUILDING NEW POWER
PARTIAL LISTING SUPPLIES WHEN YOU WANT TO EXPAND?
2400... .24 74E SOD.... .25
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7409..." ‘28 741509. 30 ALL YOUR TIME ON PROJECTS МОТ P.S.
7490..... .35 74LS90......45 KESTER 60/40
74148....75 7415138....70
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74190...-75 7415190... .85
7415244 1.00 74LS245..
CMOS
PARTIAL LISTING
Rosin core. .020 dia.
1 Pound Roll
MULTIVOLTAGE
FOR DYNAMIC RAMS ETC.
INPUT Sole Be A 220 МАС
OUTPUTS T5VDC--5AMP
*12VDC. 1AMP
—12VDC-1AMP
SOLDE
i3
co SENSE SA
74CO0..... .40 4001.... .30 12УАС--1/2 A. ^d
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74С240.. 2.35 4511... 1.15
WM120 120V 12W 19.47
SOLDERING TOOL STAND
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4 BASE & RECEPTACLE.
74C244.. 2.35
LINEAR
MC3401 QUAD ОР-АМР .... .50
MC1555 TIMER ......... Пазар 2455 .45
SINGLE VOLTAGE
FOR CMOS & TTL LOVERS
ПЧРИТ-------- 120 - 220 МАС
OUTPUT--— +5МОС---9АМР
» DIM.——9-*/2X 5 X 5
niti MOD CPS-169
ALSO AVAILABLE
120 IN 5VDC--3AMP MOD SPS 30-5...24.95
120 IN 5.8VDC--1.2AMP MOD SPS 1-5
HOBBY WRAP TOOL
AUTO-INDEX -* — wt
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FITS WP-25 WP-40 W-60
MOD PH-60
BI-FET OP-AMPS LOW NOISE
SINGLE TLO81... .75 TL071.....90
DUAL TLO82. 1.25 TLO72.. 1.50
QUAD TLO84.. 2.25 TLO74. 250
FITS WM-120
MOD PHM-120
WIRE WRAP WIRE
KYNAR #30 WIRE WRAP WIRE
PRECUT TO LENGTH THEN 1"
STRIPPED FROM EACH END.
INSERTION /
EXTRACTION TOOLS
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TOOL WITH BIT
LENGTH 100/BAG 1000/BAG| 8У/26308. .... .27.95
3.0" 1.45 7.50
3.5" 1.58 8.25
4.0" 1.65 9.00 1451416 INSERT TOOL 4.35
4.5" 1.75 9.75 MOS SAFE INSERT TOOLS
5.0'' 1.85 10.25 : MES nece MOS1416 14-16 РИМ..... 9.95
4 2- VACUUM BASED
ADD'L 0.5" UP TO A TOTA -28 PIN.....9.95
OF 10/17 pe а WRAPS AND UNWRAPS LIGHT DUTY VISE ка, a ae dU ae
л 1-1/2'' WIDE JAWS TE
BUILT-IN#30 WIRE STRIPPER 1-1/4" TRAVEL EXTRACTION TOOLS
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100' 4.3.95 500' 22 1 .95 WSUJ30...RE/LILAR...........7.25 EX2 24-40 PIN. 109-95
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CLIP AND STRIP
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WSU30M MODIFIED.........8.25
TERMS
Check, money order, VISA, or
Mastercharge. Add $3.00 for
shipping and handling, Texas
residents add 5% state sales tax.
Foreign orders add $10,00 for
shipping: U.S. funds only. |
Limited quanities on some items,
WK7 COMPLETE KIT ...37.95
ALTEX ELECTRONICS
618 W. Sunset
San Antonio, Texas
78216
1-512-828-0503
TION.TAKES А LOT
OF THE WORK OUT
OF WIRE WRAPPING,
CAS1 SOs 22:26
8K ROM 1@ FOR ж-з2е та 35
Туре in the following program. Then 18 SERDEE азы (x1; аза”
hit RUN and ENTER. Observe the results. зә NEXT ж Hes Wu IW E
m B . ее 7 ха Ши = I --
Er his If you like, you can substitute other О ERR s гари
LI | ç charactersin the print statements in Lines БӨ PRINT TAB (х); ++“
20 and 50 SB aT ла
; : м таа
Ou елата Eam -
"Try This" features short programs to Ross A. Rainwater 15 DIM aia? ee
show off your computer, impress your 305 Regal Drive =. LE a
family and friends, and tickle your imagi- Lawrenceville, GA 30245 зә Pr эмсе a”
nation when SYNC arrives at your place.
Send your contributions to: Try This,
SYNC, 39 E. Hanover Ave., Morris Plains,
NJ 07950.
4K ROM
Type in the following program. Then
RUN and NEWLINE. Type in any char-
acter or symbol when the quotation marks
appear and hit NEWLINE again. Observe
the results. Repeat until you get back to
program. Note the program.
Our thanks to:
Ken Berggren
104 Ridgeway Ave.
Louisville, K Y 40207.
Bruce Birmelin/Paramount Pictures.
SEEK OUT AND
CAPTURE THE
LANGUAGE OF MAN!
Battlefield: a24 x32 grid
Opponents: upto 26 characters ofthe :
alphabet
Weapons: your mind and the invincible
cursor
Strategy: to render your opponents
powerless by capturing them
with the cursor. Caution! To
recross your path is to abort
the mission!
Also available: Life, a simulation of biological Quantit Price
systems, with a high speed mee а Se р,
48 x 64 graphic palette. КОТ ee S л
Both well-documented games are written in C] Check enclosed. Charge ту | | Mastercard [] Visa
machine language for the ZX81 with 16K. Card No
$9.95 each. Order by phone or mail. Watch for
exciting new developments coming soon from Signature
NON-TRIVIAL SOLUTIONS КІБЕШЕ ІЗ eee
NON-TRIVIAL SOLUTIONS 806/376-5723
; а Exp. Date
12 SYNC Magazine
INL.
TS 1000 & ZX81 SOFTWARE
Remember wher. you played Hangman as a child? We've created a learning tool for you
and your children which contains 7 versions of Hangman on the ZX81.
a ж IX ELI Your child can play against the computer's 5 pre-recorded libraries of categorized words,
(each word up to 17 letters) Animals, Science, Countries of the World, States of America, and
Fruits and Vegetables.
As a special feature during the game, each program will pick a word from its own library,
ҚЫР «= к then compare it with the last 50 words played so you will not get repeat words for atleastan
hour of play. Also the computer keeps a running account of how many words you де! right
and wrong.
In the 6th version, you or your child may also play against an opponent. The computer
requests players names, keeps score and generates the Hangman graphics.
The seventh option allows you to create and save your own versions with up to 500 words
each. This is ideal for parents to create special spelling drills for their children.
Hangman is a great spelling and vocabulary tool for youngsters 6-12 years old, although
its the kind of game adults have been known to indulge in too.
SUPERMAZE* ROAD TO RICHES
SUPERMAZE is a three-dimensional maze program with
extraordinary full screen graphics that challenges you to with, | could turn it into a fortune... could be rich!" Well this is
work your way through a complex labyrinth of corridors. your dream come true -- an opportunity to show your
Enter SUPERMAZE at your own risk and carefully choose the prowess at making wise investments because you have just
been given a million dollars -- to play with!
right combinations of passageways to reach the end in the
fewest possible moves.
This graphically illustrated adventure game is full of Can you turn it into ten million? Or will you lose it all on a
hazards to impair your ability to get through it. For example as risky investment? It's up to you.
you wander through the endless corridors, you have to be ROAD TO RICHES is an entertaining and educational
ее зебарве there are йуз Mop anors you can fall computer game in which up to four players are given
through, finding yourself in another part of the maze. те ; : :
But SUPERMAZE also features уйда helpful devices to aid Иоан Eri in business ventures jn an attempt to
The program simulates a fast-moving world of investment
in which you are confronted with all kinds of investments
your journey. You can have a compass to guide you or stones
to drop along the way to let you know if you have already
passed through a section of the maze.
Written with many machine code subroutines, ranging from conservative real estate opportunities to highly
SUPERMAZE allows you to choose from ten mazes of risky Broadway shows.
increasing difficulty. In addition you can create and store г The program carefully weighs the risk of each investment
mazes of your own design. | : РАН | € and your chances for winning or losing. Like real life, low risk
: оа ue ern ail Weare gena Cn ge oat 3:5 1 usually means (but not always) low yield while high risk can
gi A map option to see where you've been but not where 22 —. J potus. - mean hitting the jackpot or financial disaster. <
you are going. i ПЦ TRI, coc Т0 Some investments give you more working capital while
е An option to find and take with you gold bars in the maze. w.. E) ый others give you equity with annual returns. j
This helps you to develop skill in maneuvering. SS UEM Мы Pit yourself against a wheeler-dealer and see if, over a
e Stones to drop along the way. 9" 3 period of seven years, you can come out on top. ROAD TO
e Optional randomly placed trap doors. AT e Қ Es RICHES is fun and informative, realistically portraying the risk
e The compass to guide you. | > 1 and skill of high finance.
16K $1495 m 8/1 .16K $14.95
PLUS MANY MORE ZX84 PROGRAMS!
WRITE FOR FREE CATALOG
SEND CHECK OR MONEY ORDER TO:
Please send me:
—,copesorHaNGMAN 51495 | SOF Я SYNC, INC.
_соріеѕ of SUPERMAZE @ $14.95 ea AS
— COPIES of ROAD TO RICHES PO Box 480, Murray Hill Station, New York, МУ 10156 (212) 685-2080
а $14.95 ea Charge to: NAME
Please indicate method of payment — C) VISA/Bankamericard
О Check, money order (no cash please) O Mastercharge ADDRESS
расы асы ee, SONS.
CITY
OE ERE ЧЕРЕН LIE LE GI RIBBON E RMR НЕ E Шы
Add $1.50 shipping and handling. STATE/ZIP
New York residents add sales tax.
8K ROM; IK RAM
Generally SYNC prefers articles in some
depth to help you get more out of your
computer. However, we receive many
short programs that illustrate a point,
demonstrate a technique, or show some-
thing the reader has found interesting.
"Just for Fun" shares these programs with
you. If you learn something, great. If you
have some fun, great. If you have some
that you want to share, send them to: Just
for Fun, SYNC, 39 E. Hanover Ave.,
Morris Plains, NJ 07950.
Graphics Loop |
Bernard Bush
One technique for squeezing more into
the limited memory of the basic ZX81 is
to use a loop. The following program
illustrates the method applied to create a
continually changing graphics display. Enter
the program. Then be sure you are in
SLOW mode. Hit RUN and ENTER and
enjoy the show.
12 РЕН GRAPHICS і пар
за LET R=INT iRNDz320@1 +1
39 LET B=INT КБМ: +1
за LET C-INT (ЕКЕМІЗ +1
за LET D-INT ЕМО #1 +1
ва LET Е-тмт tRNO #283 +1
PRINT
за PRINT
216 FOR Jdzi1 то зе
129 PRINT CHR A;
139 PRINT CHR В;
140 PRINT CHRS C;
158 PRINT CHR С:
150 PRINT CHR E:
та NEXT J
iga UNPLOT .t,.!-16
200 REM STOP WITH BREAK
Bernard Bush, Rt. 2, Mansfield, MO 65704.
14
нал" o o
Graphics Loop Il
James Grosjean
The same screen display developed in
“Graphics Loop I" can be achieved by
the following program which establishes
the loop through a technique suggested
by Ken Berggren in his “Handling Strings
from another DIMension"in this issue.
19 FOR I-1 TO 5
га LET A=RND#942
За POKE 16537.з8+1
за NEXT I
58 РОКЕ 16537.38
с 5
вә PRINT CHR$ Я; СНА B.CHR$ C.
CHR* D;CHR$ Е:
за NEXT J
POS RUN
James Grosjean, 50 Kings Rd., Chatham, NJ 07928.
Draw It
Robert S. Boynton
Many drawing programs require you to
encode a picture and then display it, but
this short program allows you to draw
and edit a detailed picture even in ІК.
Enter the program, be sure you are in
SLOW mode, and press RUN and NEW-
LINE. A black pixel will be displayed at
center screen. You can move the pixel by
using the arrow keys (no need to shift). If
you make a mistake or you want to move
without leaving a mark. press RUBOUT
and the pixel will flash. You can now
move it to a new location or backwards
to erase. Press RUBOUT again to return
to plotting. You can also put any keyboard
character into your picture by pressing
the EDIT key (no shift). and insert the
character you want in the quotation marks.
Press NEWLINE and the character will
е M
appear at the pixel location. The RUBOUT
feature works on the printed characters.
Do not go beyond the normal machine
plotting area or error B will result. If you
do not want to use the characters, you
can omit lines 110 and 130 to 150.
10 LET Хх
20 LET х-32
за LET Y=22
4@ PLOT х,у
58 IF HER UNEPLOT X.
ве IF INKEY$="S° THEN LET X-X-
7@ IF INKEY$="8" THEN LET X-X»
Sf IF INKErS3—'5o" СЕНЕР ЕТ vY-zy-
за IF INKEYS="7" THEN LET Y-Y4
100 IF INKEY$="@" THEN LET Z-NO
110 IF INKEYS$-"1" THEN GOSUB 13
HS ого га,
140 PRINT AS
150 RETURN
Robert S. Boynton, 189 David Humphreys Rd., Derby, CT 06418.
SYNC Magazine
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David B. Ornstein
The ZX81 Parser (Part 2)
In the last issue I began a discussion of
the ZX8I's parser which is a complex and
tricky combination of software tech-
niques. In this issue I will continue the
discussion by detailing the main parser
routines.
Syntax Checking vs. Execution
When you enter a line into the 7Х81,
the parser is called twice to evaluate it.
The first time is when you hit ENTER
after you have just typed a line into the
system. This call instructs the parser to
check the syntactic correctness of the
line entered. If the line is in error, an S
cursor is placed in the line at the appro-
priate position. The parser then returns
to the keyboard routine to permit the
user to correct his error. The process by
which any syntax error is shown to the
user is simple: an RST 8 instruction is
executed. This instruction is followed by
a byte which specifies the "REPORT
NUMBER". The RST 8 begins execution
by loading X-PTR with the value of CH-
ADD, the system's interpreter pointer (see
the ZX81 BASIC Programming Manual,
chapter 28). 3
If there are no syntax errors, the parser
returns, and the line is converted into its
internal representation which is shown in
Figure 1.
At this point, one of two actions will
occur. If a line number was specified, the
internal representation will be stored in
the program area. Note that, if the text of
the line is null (1.е., there is no text after
the line number), and if a line number
was given, the old version of the line, if
any exists, will be deleted. If no line
number was given, the parser will be
16
called again. This time, however, it will
execute the line.
Clearly, some method must exist to tell
the parser whether it should check-syntax
or execute the line passed to it. A bit (bit
7) in the FLAGS system variable is allo-
cated for this use. If the parser is to
execute the line, the bit will be set.
Otherwise (i.e., syntax-check only), it will
be reset. Thus the designation EXEC/
SYNTAX. A routine SYNTAX-Z (ODA6)
is used to check this bit. This routine will
return Z true if just-checking is specified.
It returns Z false (1.е., NZ) if execution is
to occur.
To clarify the use of this flag, let me
give an example. Suppose the parser is
passed the following line:
PLOT 5,10 А
The code that will be executed is chosen
by the parser. This process is detailed in
“The Parser Body" below.
ПЕГГЕГІГІГІГІ к
It must be made clear that the process
of fetching arguments and checking
syntax cannot be thought of as disjointed.
In the case of the PLOT command, as is
the case with almost all other commands
which take arguments, all arguments are
passed to Section B on the "calculator
stack." (See "Understanding Floating
Point Arithmetic: The CALCULATOR
Language," by Ian Logan, SYNC 2:2.) As
we will see in the next section, the rou-
tines used to fetch arguments check
syntax, implicitly, as they move CH-ADD
through the line—or rather the routines
used to check syntax and fetch arguments,
implicitly, as they move CH-ADD through
the line.
The Parser Body
The ZX81’s parser is table-driven. This
means that all syntax checking and exe-
cution are directed by a series of tables.
Figure 1: The internal representation of a line in Basic.
ENTER
Text of Line
Length of Line (16 bits)
Line Number (16 bits)
Listing 1: The Parser Code. — ——— ——-—
P-OFFSET:
.BYTE $8B,$8D,$2D,$7F,$81,$49,$75
.BYTE $5F,$40,$42,$2B,$17,$1F,$37
.BYTE $52,$45,$0F,$6D,$2B,$44,$2D
.BYTE $5A, 3B,$4C,$55,$0D,$52,95A
. BYTE $4D,$15,36A
SYNC Magazine
The parser code is given in Listing 1.
There are two entry points into the
parser: LINE-SCAN and LINE-RUN.
When called via LINE-SCAN, the parser
sets EXEC/SYNTAX to SYNTAX (і.е.,
0), and calls E-LINE-NO. This subroutine
is used to check the line number specified.
If the line number is outside the bounds
of a legal line number, a REPORT “С” is
issued. If the line number is valid, LINE-
SCAN falls through to LINE-RUN.
As you probably know, Ше ZX81 will
accept an expression as the argument to
an INPUT statement. The parser is used
to evaluate this expression. The first
action performed by the parser (entered
via LINE-RUN) is to check whether an
INPUT statement is being executed. This
condition is specified by bit 5 of FLAGX.
If an INPUT statement is currently being
processed, one of the two actions will
occur. If the first character is a STOP,
and the EXEC/SYNTAX flag —EXEC,
the parser will exit by using RST 8 to
signal a REPORT “D”. If the first char-
acter is not a STOP, then the parser jumps
to INPUT-REP (see Class-2). If an INPUT
statement is not being executed, a jump is
made to LINE-NULL.
The parser, continuing execution at
LINE-NULL, now checks to see if the line
is null. If it is, the parser returns immed-
iately. If the line is non-null, the parser
checks to be sure that the first character
in the line is a command. Once again, if it
is not, REPORT “С” will be issued.
Assuming that the first character in the
line is a command, the parser continues
by calculating the address of the com-
mand's entry in the parameter table. This
is done by using an offset table (0C29).
The offset table and the paramater table
are shown in Listings 2 апа 3,
respectively.
Reviewing the parameter table, you will
see that each command entry specifies
the format of a particular command. For
example, PLOT (0C98) is shown to be
comprsised of a CLASS-6 item, a comma
(,), and another CLASS-6 item. After
finding the currently executing command
in the table, the parser falls through into
a loop (GET-PARAM), which is respon-
sible for fetching successive parameter-
bytes from the command's entry.
After fetching a byte, GET-PARAM
checks its value. If the byte's value is
greater than OBh, the GET-PARAM loop
jumps to the SEPERATOR routine which
checks the character in the line against
the specified parameter-byte (i.e., ог-,
etc). If a match is found to exit,
SEPERATOR returns to the beginning of
the GET-PARAM loop. If the characters
did not match, REPORT “С” is issued via
RST 8.
July/August 1982
P-PRINT:
P-INPUT:
SET-STRLN:
REM.
111: е
CLASS-2:
INPUT-REP:
Listing 2: The Offset Table.
.BYTE $01,$14,$02 "Class
Class: 2
.BYTE $06,300 S Claes: б
.ВУТЕ $81,$0E -Crass 0
; Addr-$0E81
.ВҮТЕ $06,$DE,$05 >» Class 6
.BYTE $AB,30 ? TUB
(ODIO M
; Addr-$ODAB
.BYTE $06,$00 TE (Тазы 6
.BYTE $B5,$0E ; Аадг-$0ЕВ5
BYTE OO ДО BOC | Class 0
: Addr-SOCEC
.ВУТЕ $00,$D8,$0E ;| Glass. б
: Addr-$0ED8
.BYTE $04,$14,$06 остава 4
«BYTE ЗЕ, Ф06,505 E TNI e
.ВУТЕ $B9,$0D ; Class 6
RV
« Class «5
; Addr-$0DB9
.BYTE $04,$00 ; Class 4
-BYTE $2E,SOE | "0lase "D
; Addr-$0E2E
.ВУТЕ $05,$СЕ, ФОА ; Class 5
; Addr-SOACF
BITE- $01,900 |, Glass 4
.BYTE $E9,$0E | Става 0
; Addr-$0EEO
.BYTE $05,$09,$14 ; Class
| ; Addr-$1409
,BYTE $05,$6A,$0D ; Class 5
; Addr-$0D6A
BYTE. $005 203. 203 + (фазе O
; Addr-$03C3
; BYTE:.$03 , SAF SOE оаа
» Addar- ponar
„ВХТЕ 303£230,207 агае
| > Addr-$0730
.BYTE $06,$1А,306 ое
.BYTE $00,392,30Е ; ","
лев
|" Chass. О
Addr-30E92
CALL NZ,STK-FETCH
LD HL, FLAGX
OR oe
LD IST ЗА
EX- ОВЕН
UD -"(STRLEN,BC
DD DEST) HE
RET
POP BC
Lb o ASURLEGS)
PUSH AF
CALL SCANNING
POP AF
LD BÓ. $1321
Пре. D (FLAGS)
XOR E
AND $40
17
ЧЕ. NZ,REPORIS-C
pilo
JR NZ,CLASS-END
JRB СНЕСК-2
Listing 2 (continued)
If, on the other hand, the parameter-
byte's value is less than OB, the parser
uses another offset table (0016) to find
the address of the class handler. The class — CLASS- ^: CALL LOOK-VARS
handler is then called. When it finishes PUSH AF
execution, it will (probably) return to the DI eae МАА
beginning of the GET-PARAM loop. OR $9F
INC A
Class Handlers JR NZ,REPORT-C
A class handler is a routine used to POP AF
parse out a particular type of variable XH MI OU o
(i.e., non-constant) parameter from a line.
These items include, but are not limited CLASS-6; CALL SCANNING
to, variable names and expressions. As
class handlers perform extremely diversi-
BIT 6,(FLAGS)
fied functions, each will be presented RET №
separately with a description of the effects | 3
of its execution. REPORT-C: RST 8
BYTE $ØB
CLASS-6
CLASS-6 is the routine used to parse NC-TC-STÉ: JR NZ,CLASS-6
out an integral expression. CLASS-6 uses CALL SYNTAX-Z
a ROM routine known as SCANNING ВЕТ 2
which is a general expression parsing RST 059 ec OS TI ha
routine. Although a discussion of expres- calculator
sion evaluation techniques is beyond the .BYTE ЗАО . Stk-zero
scope of this article, it suffices to say .BYTE $34 ‚ End-calc
that the SCANNING leaves the result of RET |
its evaluation on the calculator stack. It
also sets bit 6 of FLAGS to indicate 41-4 ао
whether the value parsed was of numeric 5ҮНТАА-4: с 7, (FLAGS)
or string type. When control is returned r$
to CLASS-6, after its call to SCANNING, ee
it checks bit 6 of FLAGS. If a string LD B, $99
argument was specified, then REPORT ADD HL, BC
“C” is given. If a numeric argument was LD C, (HL)
supplied, the CLASS-6 returns. ADD HL, ВС
PUSH HL
CLASS-1 RET
CLASS-1 is called to parse out an
assignable variable name. This procedure SEPERATOR: RST 18
begins by calling LOOK-VARS, a routine GP xb
to pull a variable name out of the source JR NZ,REPORT-C2
line. LOOK-VARS returns a pointer RST 20
to the variable's record in the VARS RET
file. If the variable is not found, LOOK-
VARS creates it, and returns a pointer to т с
the created record. CLASS-1 stores Ше C-OFPSETs .BYTE $17,$25,$53, SOF »$6B,$13,$76
returned pointer and other pertinent = zc
information in system variables for later CHECK-END ip а
use. It then returns. POP BC
CLASSA CHECK -2: LD AH HL)
CLASS-4 is a routine used for a purpose СР NEWLINE
similar to that of CLASS-1. It is used to RET 2
parse out the variable name specified аа — REPORT- C2: JR REPORT-C
the argument to a FOR or NEXT com-
mand. It calls LOOK-VARS and checks | CLASS -3: СР NEWLINE
the type bits returned in the C register. It CALL NO-TO-STK
checks to be sure that both bits 5 and 6
are set in the type byte. If they are not CLASS CP oA
set, REPORT “С” is given. If the variable
name was valid (i.e., a single-character СІ,А55-5: pap- ВС
numeric scalar), CLASS-4 will jump into тт TOK E
the middle of the CLASS-1 routine which пара : ар а
will then proceed by storing Ше informa- | LD HL 3 (T ADDR)
tion on the variable in the appropriate LD C (HL)
system variables.
18 SYNC Magazine
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ADVENTURES FOR OSI, TRS-80, TRS-80 COLOR, SINCLAIR, PET, VIC-20
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In Adventuring, the computer speaks and
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Except for Quest, itself unique among Ad-
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Authors note to players — | wrote this one
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CIRCLE WORLD by Bob Anderson — The
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Editors note to players — In keeping with
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wrote a very large adventure. It has a lot of
rooms and a lot of objects in them. It is a very
convoluted, very complex adventure. One of
our largest. Not available on OSI.
HAUNTED HOUSE by Bob Anderson — This
one is for the kids. The house has ghosts, gob-
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designed for the 8 to 13 year old. This is a
real adventure and does require some thinking
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Authors note to players— This one was fun
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DERELICT by Rodger Olsen and Bob Ander-
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Authors note to players — This adventure
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This ship was designed to be perfectly safe for
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NUCLEAR SUB by Bob Retelle — You start
at the bottom of the ocean in a wrecked Nu-
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up. Save the ship, raise her, or get out of her
before she blows or start WWIII.
Editors note to players— This was actually
plotted by Rodger Olsen, Bob Retelle, and
someone you don't know — Three of the nas-
tiest minds in adventure writing. It is devious,
wicked, and kills you often. The TRS-80 Color
version has nice sound and special effects.
EARTHQUAKE by Bob Anderson and Rodger
Olsen — A second kids adventure. You are
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To save yourself, you have to be a hero and
save others first.
Authors note to players — This one feels
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Authors note to players — This is a very
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MARS by Rodger Olsen — Y our ship crashed
on the Red Planet and you have to get home.
You will have to explore a Martian city, repair
your ship and deal with possibly hostile aliens
to get home again.
Authors note to players — This is highly
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way simple —playing time normally runs from
30 to 50 hours — but it is constructed in a
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venturing and get used to the game before
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ADVENTURE WRITING/DEATHSHIP by
Rodger Olsen — This is a data sheet showing
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Data sheet - $3.95. NOTE: Owners of OSI,
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PRICE AND AVAILABILITY:
All adventures are $14.95 on tape except
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Listing 2 (continued)
SCAN-LOOP:
GET-PARAM:
INC HL
О-В, СИБ)
ЕХ DE: HG
PUSH BC
RET
CALL LOOK-VARS
LD (FLAGX),$00
JR NC,SET-STK
SET 1,(FLAGX)
JR NZ,SET-STRLN
RST 8
.BYTE $01
CALL Z,STK-VAR
BIT 6,(FLAGS)
АСМ ,SET-~STRIN
XOR A
CALL SYNTAX-2Z
LD (FLAGS),O01 ‚ Set up SYNTAX-
checking only
CALL E-LINE-NO
CALL SET-MEM
LD НІ,ЕВЕ NR
LD (HL),$FF
LD: —DIBBAGX
BIT 5,(HL)
JR 2,LINE-NULL
Ср. "Shop" s Ye ЕЗ Hex
LD - нъ)
JP NZ,INPUT-REF
GALL SXNTAX-Z
RET 7
RST 8 : Error "D"
.BYTE $C
RST 8 ‚ Give REPORT "9"
.BYTE $48
RST 8
LD B, $00
CP NEWLINE
RET a%
LD С, А
RST 5220
LOD- -AG
SUB. ФЕ
JR С,КЕРОКТ-С2
LD C,A
LD. -HL P>OFESET
ADD HL,BC
LO зе CHL)
ADD HL,BC
JR GET-PARAM
LD HL,(T ADDR)
BD ASCHL
INC HL
LD (T ADDR),HL
LD BC,SCAN-LOOP
PUSH BC
LD C
СР $gB
JR NC,SEPERATOR
SYNC Magazine
CLASS-2
Тһе CLASS-2 routine is responsible for
parsing out the value assigned to a var-
iable (previously specified by CLASS-1)
in a LET or INPUT statement. The
expression is evaluated by SCANNING.
The type of the expression evaluated is
then checked against the type of the
variable (name) stored by CLASS-1. If
the types are not equal, then REPORT
“С” 15 issued. If, on the other hand, the
types do mix, a jump is made to the LET
routine at 1321h.
CLASS-5
IF, PRINT, LPRINT, FOR, REM,
LOAD, DIM, and SAVE all have CLASS-
5 as their last parameter. The CLASS-5
byte (05h) is followed by two bytes which
form an address. The address specified is
that of the handler for that command.
The command handler is the routine that
actually performs the action specified by
the command (i.e., placing a dot on the
screen, in the case of a PLOT command).
By reviewing the code for CLASS-5, you
will see that, after POPing its return
address (probably OCF4h), its gets the
next two bytes from the command's entry
in the parameter table. It combines these
bytes and jumps to the address specified
by the resulting word.
Before executing the jump, a CALL is
made, conditionally (if the Z-flag is set)
to CHECK-END. This routine checks to
be sure that the next character in the line
specifies an епд-о те (і.е., a NEW-
LINE). If it does not, REPORT “С” is
given. If the character is a NEWLINE, a
return is made.
CLASS-0
CLASS-0 is simply a CP A instruction.
This instruction is commonly used by Z80
programmers to set the Z-flag. After
executing this instruction, CLASS-0 falls
through to CLASS-5. CLASS-5 will then
CALL CHECK-END, as the Z-flag is set.
——————————————— Listing 3: The Parameter Table. —— — — — —————— — — — —————
P-RAND: .BYTE $03,$6C,$0E | Class 3
; Addr-SOE6C
P-LOAD: .BYTE $05,$40,$03 :; Olass-5
; Addr-$0340
P-SAVE: .BYTE $05,$F6,$02 ) Claes.
; Addr-$02F6
P-CONT: .BYTE $00,$7C,$0E ; Class O
: Addr-$0E7C
P-CLEAR: .BYTE $00,$9A,$14 ‘i Class о
; Addr-$159A
P-CLS: .BYTE %00,%2А,%0А ; Class 0
: Addr-$0A2A
P-PLOT: .BYTE $06,S1A,$06 : Class 6
.ВУТЕ $00,$AF,$0B ua 2
S Olaes-6
; Class O
; Addr-$0BAF
F-UNPLOT: .BYTE $06,$1А,$06 |: Ofass 6
.ВУТЕ 900,ФАЕ,ФОВ ДЕ Па
: Class 6
; Class 0
; Addr-$0BAF
P-SCROLL: .BYTE $00,$0E,$0C | Class 0
; Addr-$0COE
P-PAUSE: .BYTE $06,$00,$32 | Class 6
.BYTE ФОЕ ; Class O
; Addr-$@F32
P-SLOW: „ВУТЕ $00,$2B,$0F |; Class 0
; Addr-$0F2B
P-FAST: .BYTE $00,$23,$0F ; Class 0
: : Addr-$0F23
P-COPY: .BYTE $00,$69,$08 : Class 0
; Addr-$0869
P-LPRINT: .BYTE $05,$CB,$0A | Claes 5
; Addr -$0ACB
P-LLIST: .BYTE $03 ,$2C.$07 | .Olass 3j
; Addr-$072C
July/August 1982
CLASS-3
CLASS-3 handles the argument speci-
fied after a RAND, LIST, LLIST, or RUN
command. This element can be either a
NEWLINE or an integral expression. If a
NEWLINE is given without any expres-
sion, a default of 0 is assumed, and pushed
onto the calculator stack. If a number
was specified, CLASS-6 is CALLed to
parse the expression. After pushing the
appropriate number onto the calculator
stack, CLASS-6 returns to CLASS-3.
CLASS-3 then falls through to CLASS-0.
In the next issue I will discuss the
command handlers themselves.
Once again, I wish to extend my utmost
gratitude to Ian Logan for his hard work
in disassembling Ше 8K ROM. АП labels
in this article come from the result of his
work: The Sinclair ZX81 КОМ
Disassembly, Part A.
Until next time, same relativistic time
period, same non-Euclidian universe. Mg
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21
4K ROM (8K ROM); 1K RAM
їп егп sync = —
Alan Groupe, Michael Tardiff, and Ivan Zatkovich
Two to the What?
Recently, a cousin from Lincolnwood,
Illinois, came out to visit. Along with him,
he brought a couple of "extra credit"
problems given him by his eighth grade
science teacher.
One of the problems was to calculate 2
to the 420th power. The problem came
with the following restriction: "You can't
use a computer." Since no commonly
available computer can store a number
this large with perfect accuracy (remem-
ber, floating point numbers are only
approximations of a number), this restric-
tion seemed unnecessary.
You have probably already guessed,
though, that with some thought and a few
tricks, you can solve this problem using a
computer. It should also come as no
surprise that we are going to show you
how to do it on your ZX80/81.
It does seem to us, however, that any
eighth grader who could figure out how
to solve this problem on a computer is
well on the way to becoming a clever
problem-solver who can make good use
of available tools, and, therefore, deserves
the extra credit. Lincolnwood School
District, take note.
To solve this problem on a ZX80/81 or
on any computer, you first have to under-
stand how to do it by hand.
Unless you are a child prodigy, you
cannot handle a number as big as 2 to the
420th either. The best way to deal with
things too big to handle all at once, of
course, is to break them down into “bite-
size" chunks. In this case, the most
obvious method probably would be to
treat each digit separately. You could
take 2, multiply it by 2, take that answer
and multiply it by 2 again, and so on, 419
times. When the numbers begin getting
too large to multiply in your head, you
would move from right to left, multiplying
a digit by 2, adding in any carry from the
22
previous digit, and carrying into the next,
if necessary. Just like in school, right?
While the ZX80/81 cannot handle
numbers as large as 2 to the 420th, it can
handle numbers as big as 32767 (decimal).
Rather than doing the calculations one
digit at a time, as you would do by hand,
it is a simple matter to have the ZX80/81
multiply four digits at a time. Listing 1
gives the program for calculating 2 to the
420th. This was written on the ZX80 4K
ROM, but it works also on the ZX81 if
you make this change:
180 PRINT А); #8”;
Since the answer to our problem is 127
decimal digits long (How do we know?
Trust us.), we can store it in an array of
32 integers. This is done in line 10. Lines
20-50 initialize our answer to 1 (2 to the
zero-ith power). Lines 60 through 160 are
the main loop of the program and multiply
A by 2 420 times. C is the carry from one
"digit grouping" to the next and is cleared
in line 70. (There is no carry, of course,
into the rightmost digit.)
Lines 80 and 90 set up a backwards
FOR-NEXT loop going from 32 down to
1, covering each digit group from right to
left. We could have numbered the digit
groups in the other direction, but then we
would have needed a reverse loop to print
out the result, so it did not make much
difference which way we went. Line 100
multiplies the current digit group by 2
and adds in the carry from the previous
digit group. Line 110 clears the carry,
since we do not as yet know whether
there is to be a carry out of the current
digit group. Line 120 skips over the carry
processing if the current digit group is
within range (0-9999). Lines 130 and 140
do the carry processing by bringing the
digit group back within range and setting
the carry into the next group to 1. You
should satisfy yourself that this is correct.
Line 150 closes the loop at line 80 and
proceeds to the next digit group. Line 160
closes the loop at line 60 and proceeds to
the next doubling. Calculations are now
finished, and lines 170 through 190 print
out the result.
Note that the format of the output is
rather sloppy. The reason for this is that
some of the digit groups may be less than
1000, and in order for the result to be
printed together, program lines would
have to be added to print these groups
with leading zeros. While this is not
particularly difficult, it would tend to
make the program more complicated. If
you have sufficient RAM, the inspiration,
and a compulsion for neatness, see if you
can alter our program to "prettyprint."
When run, the program grinds away
for a little over four minutes before
returning with the answer. Compared to
pencil and paper, that is not bad. But
consider this: on the first iteration of the
main loop (lines 60-160) the variable
A(32), which is originally 1, is multiplied
by 2, giving 2. But A(1) through A(31),
while being equal to 0, are still multiplied
by 2. On the second iteration this is also
true. In fact, most of the four minutes are
spent multiplying 0 by 2!
This provides us with a good example
off how careful planning can make a
program run faster. If you think through
a problem ahead of time, you can cut out
the pointless work and free your ZX80/81
to do the real work of calculating or
searching or whatever. Sure enough, there
is a simple way to “optimize” our program
to eliminate the wasted work of multi-
plying 0 by 2.
If you keep a pointer (call it "P") to the
most significant (leftmost) non-zero digit,
and stop the right-to-left multiplication
loop (lines 80-150) at that point, you avoid
the unnecessary multiplications. Remem-
ber, though, to move this pointer to the
left when you carry out of that digit (in
this case, the digit to the left will now be
non-zero).
If that is a bit tough to follow the first
time through, add the lines in Listing 2
for 4К ROM or Listing 3 for 8& ROM.
Then trace through the program using
pencil and paper. You will see how the
unnecessary work is avoided.
SYNC Magazine
Software Publishers —Analyze the NEED!
The TIMEX and SINCLAIR ZX systems are cassette-based. Everything
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Software Publishers —Qualify the SOURCE!
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SYNC Program Listings
Readers should note the following
conventions used in the program listings
in this issue:
# — The number symbol is used in
PRINT statements to show necessary
spaces.
"A"— The underline is used in PRINT
statements to indicate graphics. Press the
key designated in whatever way your
machine requires to get the graphic.
INPUT — In PRINT statements when
a word or token is underlined enter the
word from the keyboard rather than type
it in letter by letter. This is a memory
saving technique.
After typing in a program line, you
must put the line into your program. On
Ше ZX80 and ZX81 with 8K ROM this is
done by hitting the NEWLINE key. On
the ZX8I the same thing is done by hitting
ENTER. The words are used interchange-
ably.
A number followed by a b is binary; a
number followed by h is hex.
Line 55 initializes our new pointer to
one significant digit group. This is because
A(32), or rather, A(P), is the only digit
group with anything in it. Line 80 has
been changed to loop through only the
significant digit groups. You should verify
that this is correct.
Lines 143 through 147 have been added
to the carry processing section. They will
only be executed when there is a carry
out of a digit group. Line 143 checks to
see if this is a carry out of the currently
most significant digit group (the one P
points to). If not, this is simply a normal
carry, and carry processing is done.
Otherwise, lines 145 and 147 move the
pointer one digit group to the left and set
that digit group to 1 (the carry out of the
previous group).
With this modification in place, the
program takes just under three minutes,
an improvement of over 35 percent.
It should be apparent that you can use
this same technique to calculate other
"big" numbers. If you really want to
impress your friends, amaze yourself, and
give your ZX80/81 a workout, try calcu-
lating that wonderful constant, pi, to a
hundred places or so. You will have to
solve a few problems along the way, but
you have two months until the next issue
of SYNC comes in the mail...right?
By the way, in case you did not have
your ZX80/81 with you as you read this
column (perish the thought!), the answer
to our problem is (drum roll, please):
2, 707, 685, 248, 164, 858, 261, 307, 045,
101, 702, 230, 179, 137, 145, 581, 421, 695,
874, 189, 921, 465, 443, 966, 120, 903, 931,
272, 499, 975, 005, 961, 073, 806, 735, 733
604, 454, 495, 675, 614, 232, 576. а
Listing 1: 2 to the 420th (4K ROM). —
лə OIM я (32?
из Hae ШЕТТЕН
PH вбниебво не
170 FOR I-1 Ta 22
188 PRINT BRI).
198 NEXT I
— ç Listing 2: Eliminating 0*2 (4K ROM). .
55 LET P=32
за FOR Ісі TO 32-P-«1i
143 IF NOT Ііз-Р THEN GOTO 158
145 LET P3P-l
147 LET ЯР} =1
_ — . Listing 3: Eliminating 0*2 (8K КОМ).
55 LET P=32
за FOR І-і T2 зе-е++
143 ТЕ 11 < зе THEN GOTO 158
145 LET P-P-1
147 CET Ру =1
DON'T JUST EXPAND YOUR MEMORY.
EXPAND YOUR HORIZONS.
Are you ready to put your ZX-81 to
work on some tough processing prob-
lems? Would you like to use your ZX-
81 in monitoring or control applica-
tions? Then consider the Wisconsinc
16K/32K memory board with I/O
ports.
The Wisconsinc memory board is de-
signed for economy and flexibility. We
offer kits ranging from a bare board
and edge connector for the budget
minded to a complete 32K with ports,
aluminum enclosure, and a power
supply with sufficient capacity to
source 500 ma to peripheral loads. All
kits include complete schematic and
instructions for the 32K with ports to
allow easy expansion as your needs
change. or as your budget allows.
Wisconsinc s I/O ports consist of two
8-bit LS TTL input ports and two 8-bit
latching output ports. The ports are
readily accessed using BASIC PEEK
and POKE commands. or can be ac-
24
cessed at very high speeds with user
subroutines. The applications for ports
are limited only by your imagination.
With suitable external circuitry, they
are useful for data acquisition and
storage. joystick interface, music
synthesizer, realtime clock inputs,
home security systems, environmen-
tal monitoring and control, and much
more. And the best part is that Wis-
consinc s ports may be added later as
the need arises; port kits come with
headers and ribbon cables.
Even if you don t need the ports. you II
find Wisconsinc s 32K memory to be
easy to use, requiring only two simply
BASIC commands to move the stack
and re-initialize your ZX-81, providing
16K for BASIC programs and 16K
useful for large arrays and variables.
This allows the use of large arrays and
character strings, and will offer new
possibilities in scientific and business
applications, especially for engineer-
ing or accounting students.
16K memory kit
32K memory kit
Bare board. connecter
16K add-on kit
Kit repair service
Wisconsin residents add sales tax.
Please add $4.95 for shipping and
handling. Check or money order only.
Allow 4-6 weeks for delivery.
Get the most from your ZX-81, and put
the world within reach of your key-
board. Think about it. You can only do
so much with software. Sooner or later
you И wish you had ports.
WISCON
Wisconsinc Electronics
PO Box 332
Milton WI 53563
SYNC Magazine
PRINT
For 59995 you can have a
full powered personal computer.
Most people know by now that the
ZX81 from Sinclair Research is the
lowest priced personal computer in
The ZX81 is also very convenient to
use. It hooks up to any television set to
produce a clear 32-column by 24-line
the world. display. And you can use a regular cas-
But serious program- ~~ — 7777773, sette recorder to store and
mers are looking for more Ip == recall programs by name.
than a low price. They're ||: What you get. When
looking for true computer | you order your ZX81, you
power. And that's where get everything you need to
the ZX81 surprises a lot start programming.
of people. It comes with connectors
Just look at the key- for your TV and cassette
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Options and add-ons. Like any
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Its 1K memory can be expanded
board and you'll get
some idea of the
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You have 10 days to try out the
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Why wait any longer? With the Sin-
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Call toll free 800-543-3000. Ask
к for operator #509. In Ohio call:
E 800-582-1364; in Canada
call: 513-729-4300. Ask
for operator #509.
computers. The ZX81 offers features to over 16K just by plugging the Phones open 24 hours
found only on computers costing two Sinclair Memory Module onto a day, 7 days a week.
or three times as much. the back of the unit. The cost #4 Have your MasterCard
Just look at what you get: _ is only $49.95. ч or VISÀ ready.
е Continuous display, including mov- Sinclair has also published These numbers are for
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е Multi-dimensional string and nu- settes fór your ZX81. We're con- Free guide to programming | information, please
merical arrays stantly coming out with new pro- write: Sinclair Research Ltd.,
* аас чо and scienti- зы SO it e. you our TS 2 Sinclair Plaza, Nashua, NH 03061.
fic functions accurate m= software catalog when you order
to 8 decimal places C. your computer. To order call toll free: 800-543-3000.
How did we do it? The
question most often asked
about the ZX81 is, "How
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Unique one-touch (Ху,
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е Automatic syntax er- power cost so little money?"
rordetection and easy 16K Memory Module The answer is that Sinclair
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Built-in interface for ZX Printer
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A comprehensive programming
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For example, our unique Master Chip
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The success of the ZX81 speaks for
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stand behind our product. If anything
goes wrong in the first 90 days, we'll
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| ee MAIL TO: Sinclair Research Ltd., |
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PRICE* QTY. AMOUNT
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Sinclair technology is also available in Timex/Sinclair
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sinclair
Book Review
Understanding Your
Understanding Your 2 Х81 ROM Бу Dr.
Ian Logan. Melbourne House Ltd., Glebe
Cottage, Station Rd., Cheddington, Leigh-
ton Buzzard, Bedfordshire LU7 7NA, U.K.
162 pp.; paperback. Available directly
from the author for $18 (airmail). In U.S.
$19.95 from: Gladstone, Heuristics, Sin-
clair Place, Softsync.
SYNC readers will recognize Dr. Logan
as a major ZX80/81 expert whose writings
are well worthwhile. Understanding Your
ZX61 ROM is no exception. The book is
written for a serious beginner who has a
fairly good knowledge of Basic and wishes
to take advantage of Z80 machine code
execution speed. It supplements, but does
not replace, the ZX81 manual which must
be used as a reference. In many ways this
book is an extension of Dr. Logan's article
"An Introduction to Machine Code" in
SYNC 1:6.
The book falls logically into five parts.
The first is a brief review of the Z80
CPU, its registers, and its instruction
format. Next a quick introduction to the
internal arithmetic and number base
manipulations required is included.
Thomas L. Keeney, 9629 Dortmund, Huntsville,
A] 35803.
8K / 16K PROGRAMS
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28
ZX81 ROM Thomas L. Keeney
The second part is a discussion of the
Z80 machine code instruction set grouped
by function. Examples are drawn liberally
from the 8К ROM. Dr. Logan includes 26
additional examples in the form of simple
Basic programs which can be entered and
executed in the 1K memory.
A detailed examination of the relevant
parts of the 8& ROM makes up the third
part. The discussion is limited, however,
to those routines which the user can
reasonably access and use. Again, simple
Basic programs detail the manner in
which ROM based subroutines can be
applied to a program. A simple USR-
(address) will not work with most of them.
ROM functions for report generation,
character printing, keyboard input, and
display generation are discussed.
The fourth part might properly be
called “Getting Started in Machine
Code.” Dr. Logan introduces machine
code programming by treating it as an
extension to Basic. His technique of
writing Basic programs that mimic
machine code is unique to my experience.
This appears to be such a good teaching
method that it should become wide-
spread. Of course, the technique is possi-
ble only because the Sinclair Basic can
Navak Command дла
highly advanced уел-
Sion of Battleship.
(16K Game)
For full listing and
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send $3.00 to:
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accept variables of any length. Such
concepts as flowcharting and program
structure help get the beginner started.
Dr. Logan leads the programmer to think
in terms of the special needs of the CPU.
Finally, he discusses the integration of
the Basic and machine code into one
program. Demonstration programs illus-
trate the whole process.
The fifth part consists of appendixes.
Complete listings of the more important
8K ROM routines are given as well as the
usual tables of machine code language
instructions, decimal-hexadecimal conver-
sions, and keycodes.
Obviously, the book contains a great
deal of information, and you would pro-
bably want to keep it as a reference.
However, the book can be made easier to
use with three improvements.
First, the book clearly needs an index
and a revision of the physical arrangement
of some of the contents. For example, the
Z80 instructions set descriptions and the
8K ROM examples are separated from
the short programs illustrating their use.
This forces the reader to flip back and
forth between references. I spend a lot of
time with my fingers stuck in several
pages to keep track of the relevant subject
references while trying to apply the infor-
mation to a particular programming pro-
blem.
Second, since the 8K ROM is decimal
oriented, the inclusion of decimal equiva-
lents for the hexadecimal numbers would
remove some frustration for the beginner.
Granted that a book on machine language
needs some hex code information and
examples, but the extensive use of hexa-
decimal leads to some problems. For
example, the table of machine code
instructions in Appendix ii is useless as a
quick reference until the reader himself
enters the decimal equivalents.
Third, a more durable type of binding
that will allow the book to lie open and
flat so that the reader can use both hands
to enter program listings is needed. The
pages are starting to fall out of mine, and
I will soon ring bind it myself.
In spite of these three complaints, the
fact that I have worn out Dr. Logan's
book is an indication of how useful I have
found it to be. The fact that I intend to
repair it is an indication of how valuable I
think it will continue to be. It contains a
tremendous amount of information and is
well worth the cost. Understanding Your
7Х81 ROM would be a valuable addition
to most ZX80/81 libraries, and for the
serious programmer it should be high on
the list.
SYNC Magazine
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Hardware Review
Sinclair ZX Spectrum
David Tebbutt
Well, he's done it again, hasn't he?
Uncle Clive has gone and shown the
world how to produce a decent colour
personal computer at the sort of price
only he can conceive. Two versions of
the Spectrum are available — 16k and
48k at £125 and £175 respectively,
including VAT. If you want to upgrade
your 16k machine to 48k later on, it
will cost you £60. At the moment, the
machines are available only by mail
order. The Spectrum (ZX Spectrum to
be precise) offers colour, high resolu-
tion graphics and sound and, at the
price, it has just got to be the best
value for money around.
Like most computers at this level,
the Spectrum plugs into the domestic
television and uses a normal cassette
recorder. The ZX printer can be
attached and, with a little modification,
ZX81 programs will run happily on the
Spectrum. A £50 miniature disk drive
(the ZX Microdrive), communications
facilities and an RS232 interface will be
announced later on.
Hardware
The Spectrum measures just 233x144x
30mm and weighs in at 520 grams
excluding the separate power supply
and cables. It looks extremely elegant
and, unlike its predecessors, it has keys
that actually press down.
You'll not be surprised to learn that
there are hardly any components inside
the machine: 14 chips, a UHF modula-
tor, a piezo-electric ‘speaker’ and ап
assortment of capacitors, resistors,
diodes, crystals and a coil make up the
complement. I swear that some of my
crystal sets had more in them. All this
is mounted on a single board and,
looking underneath this production pro-
totype, I notice that there’s not a single
patch. The only odd thing about it is
that there’s a big blob of green plasti-
cine stuck around the coil. The coil on
the review machine does whistle a bit
but I understand that production
machines come with suitably lacquered
coils to eliminate this problem.
Reprinted with permission of Personal Computer
World, 14 Rathbone Place, London WIP IDE,
England.
30
A hefty edge connector at the back
brings out just about every signal you
could wish to have. This is used for
printers, communications and disk drive
connections, Inside there are two spare
sockets which accommodate each end
of the 32k memory expansion board.
This is a great improvement on the
ZX81 memory expansion which tended
to drop off the back of the machine at
the least provocation. Taiking of sockets
(well I was, just now), every chip except
the ULA is socketed. The reason the
ULA isn't is because it gets darned hot
— putting it on the PCB allows the heat
to dissipate better.
The keyboard comprises a one-piece
grey rubber moulding mounted over a
pressure-sensitive membrane. The keys
poke up through holes in a black metal
plate and I must confess the feel is more
that of a calculator than a typewriter.
Most keytops have three symbols on
them and, in addition, most of them
have another two associated inscrip-
tions printed on the metal surround. If
you're anything like me you'll find
yourself reading the whole keyboard
each time you want to find a function.
You do get used to it after a while: in
my case it took a couple of days. I
found that red symbols on grey keytops
are quite difficult to read and, thinking
my eyesight might be going, I showed
the machine to a number of friends, all
of whom had the same difficulty. I
showed it to my 1l.year-old and һе
thought it was just fine, though.
A power supply is included in the
price, so there's not a lot of point
risking one of your own and blowing
the Spectrum up. The two cassette leads
terminate in 3.5mm jack plugs so be
sure that they work with your recorder
before you embark on any major pro-
grams. It took me four or five tries
before I found the right volume setting
on my tape recorder. Once this was
found, though, program loading presen-
ted no problems.
1 tried the Spectrum on three tele-
visions and the results matched the
quality of the sets used. The display
comprises 24 lines of 32 characters with
the bottom two lines reserved for
messages and entries. The display can
also be regarded as 176 x 256 resolution
for graphies work. High resolution
graphics work is best done in two
colours as you will see in the Firmware
section of this review. The screen,
border and individual characters can
each take on one of eight colours and, in
addition to this, characters can be bright
or flashing. Other screen attributes
like inverse and overprinting relate to
the whole screen. More on these later.
The single channel BEEP facility
is about what you'd expect from a
piezo-electric speaker. It does sound
slightly better amplified from the
cassette port but it’s still pretty awful.
A couple of octaves around middle
C aren’t bad; but the other eight are
best used for sound effects. At the hign
end they warble and at the low end they
grate — BEEP is a refreshingly honest
description.
Really, there’s not a lot more to say
about the hardware. It is a very profes-
sional job; looks smart, works well and
manages to squeeze 191 legends on to
just 40 keys!
Firmware
Here’s a new section for PCW Bench-
tests. All the software on the review
machine was in the ROM chip which
also contained the character set. This
time Sinclair has gone for a basic ASCII
set (upper and lower case) with the
addition of both built-in and user-
defined graphics characters. Outside of
the range SPACE to QUOTES (32 to
126), many of the codes have special
values relating to Spectrum keys and
functions. For example, you’ll find a
copyright symbol key. (Now why didn’t
anyone else think of that?) You can
define up to 21 characters of your own.
Two screen tables are maintained in
memory — one for the displayed charac-
ters themselves and the other for the
attributes which describe how they’re
to be displayed. These attributes can be
tested from within a Basic program. The
character colour is referred to as INK
while the background colour is called
PAPER. Isn't that sensible? Each
character can have its own value for
INK, PAPER, FLASHING, BRIGHT-
NESS, INVERSE and OVER. The last
two should be explained: INVERSE
simply means that the dots which form
the character are printed in the PAPER
colour while the PAPER is printed in
the INK colour. OVER is special: it
allows you to merge a new character
with the one already at the screen posi-
tion. The rules are that two INKs or two
PAPERs print PAPER otherwise it
prints INK. This means that you have a
neat way of removing the last thing
SYNC Magazine
printed and restoring what was there
before it.
By now you have probably realised
why it is best to stick to two colours
when doing graphics work. Since the
colour of the INK and PAPER relates to
a whole character position, then each
time a new colour graphics point is set,
all other set points within the boundary
of that character are set to the new
colour. This makes for a very curious
effect to say the least.
Mathematical accuracy is to 92
decimal digits and a fairly full range of
mathematical functions is accessible
from the keyboard. While on the sub-
ject of keyboards, this one has a built-in
software ‘click’, an upper-case lock key
and automatically repeating keys. Like
the ZX80 and ZX81 before it, the
Spectrum makes great use of single
stroke keyword entries. In fact, I think
every standard function and command
is obtainable in this way. You'll even
find things like >= and <= occupying
their own pieces of grey rubber.
Basic
The Spectrum comes with a very useful
version of Basic. It will be quite familiar
to anyone who is used to the Microsoft
types of Basic and a doddle to learn for
those new to the language.
Rather than go through all the
features and functions of the language,
I have summarised them in a separate
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box. Here, РП just comment on the
unusual and interesting aspects of this
particular implementation. Unlike some
Basics, it is a teeny bit strict about
things like using LET before assigning a
value to a variable name or putting
GOTO after a THEN. My view is that
this is all jolly good discipline and it
is more than compensated for by the
fact that Spectrum pops in all those
spaces which make programs so much
easier to read. Of course, once you've
found your way round the keyboard,
the single stroke keyword entry is a
joy. (Гуе got a feeling I said that in my
last two ZX reviews.)
SAVEing and LOADing cassette
tapes gives plenty of scope on this
machine. You can save a program nor-
mally, you can save it so that execution
starts automatically when it is reloaded,
you can save arrays, you can save parti-
cular chunks of memory and if you
want to keep a pretty picture you've
created then you can use the SCREEN$
option to save that too. All saved pro-
grams can Бе verified after saving. The
screen save can't be verified because the
display is changed during the verify
program and it would not then match
that held on tape. The LOAD command
can, of course, handle any tape created
by SAVE. The MERGE command
allows you to merge a program on tape
with one already in memory. Program
lines which are duplicated are over-
8K/16K
Now
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and if you have the 1
written while all others are suitably
interleaved.
The graphics facilities are great fun.
You can draw straight lines, curves and
circles on the 176x256 pixel (PICture
ELement, or dot) window. Position 0,0
is at the bottom left-hand corner of the
screen. You can define up to 21
graphics characters of your own which
is a superb feature if you’re into writing
your own Space Invader or Pack-Man
games. I had a lot of fun drawing and
animating little people on the screen.
The nice thing is that you can do all
this sort of thing without leaving
Basic. A BIN (binary) notation has been
introduced which allows you to define
numbers as a series of Os and 1s — just
the ticket for designing funny charac-
ters. Each character comprises eight
lines of eight points, so a succession of
eight BIN numbers is all you need to
define such a character. Another use for
user-defined graphics is to squeeze some
extra colours out of the machine. If you
lay out the 64 pixels like a chess board
and choose suitable INK and PAPER
colours then you can get some interest-
ing effects. Most of them will be awful
but persevere — some will be good.
You won’t be surprised to learn that
line drawing and circle plotting are
achieved using the DRAW and CIRCLE
commands. A PLOT command allows
you to plot single points. POINT
enables you to find out whether a parti-
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cular pixel is set. You always DRAW
from where oe thinks you are on
the screen. For example, a command
DRAW 10,10,pi would draw a semi-
circle ending up 10 places to the right
and 10 above the current position. A
fraction of pi would provide a different
arc while zero, or no third argument
(DRAW 10, 10) would draw a straight
line. The curve can be drawn on either
side of the centre line by making
the third argument a positive or nega-
tive number.
The CIRCLE command uses three
arguments: x-axis, y-axis and radius.
Remember, the OVER command can be
used to erase something already drawn.
I used this feature in conjunction with
DRAW, PLOT and CIRCLE to create
cartoon effects. OVER is also useful for
embedding text in a drawing. When set
on, the text merges with the existing
lines in the drawing. When set off it
prints the full 8x8 character, completely
replacing anything already displayed at
that position. Incidentally, SCREEN$
can be used to return details of the
contents of a character position. Used in
conjunction with the PRINT AT
command, this could be a good way of
Spectrum Basic
Functions
ABS ACS AND ASN ATN ATTR BIN CHR$ CODE
COS EXP FN IN INKEY$ INT LEN LN NOT
OR PEEK PI POINT RND SCREEN$ SGN SIN SQR
STR$ TAN USR VAL VALS
Operations
+ — * | => < <= >+ <>
Statements
BEEP DATA GO TO LOAD. ПАТА OVER RETURN
BORDER DEF FN IF. .THEN LOAD. .CODE PAPER RUN
BRIGHT DELETE INK LOAD. SCREEN$ PAUSE SAVE
CAT DIM INPUT LPRINT PLOT SAVE. .LINE
CIRCLE DRAW INVERSE MERGE POKE SAVE. ПАТА
CLEAR ERASE LET MOVE PRINT SAVE. .CODE
CLOSE FLASH LIST NEW RANDOMIZE SAVE. SCREENS
CLS FOR. .TO. .STEP NEXT READ STOP
CONTINUE FORMAT LLIST OPEN # REM VERIFY
COPY GOSUB LOAD OUT RESTORE
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ALL ON ONE CASSETTE FOR
making your program find a suitable
place to print a sort of ‘label’ on a draw-
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row and column at which printing
should start.
A few instructions I particularly
noticed as I went though the manual
were READ, DATA, RESTORE and
УАЗ. READ and DATA are old
friends although I can't remember
them being on previous ZX machines.
Using the DATA command you can pro-
vide lists of information at the begin-
ning of a program, Each READ instruc-
tion takes the next word from this list.
RESTORE can be used to set the DATA
pointer to any DATA statement. VAL$
baffles me — it strips the outside quotes
from string expressions and returns the
string value of the result. Perhaps some
kind reader would care to suggest a
worthwhile application for this feature.
Now let's have a look at our honestly
named friend, BEEP. There's not a lot
to tell, really, except that you can
control both pitch and duration. Notes
below middle C are represented by nega-
tive numbers, those above by positive.
Twelve numbers make an octave. (If
you look at a piano keyboard you'll
find that there are seven white notes
and five black notes per octave.) Middle
C is zero. The duration is expressed in
seconds or fractions of a second. As I
mentioned earlier, the sound isn’t
brilliant but it has the saving grace of
An Essential addition to your 16K RAM 2X81
TOOLKIT (written by Paul Holmes)
Provides the following additional facilities:-
Line renumber - you state starting number and increment
value.
GOTO's and GOSUB's included in line renumber
Search and List - Searches for and lists every line
containing specified character
Search and replace - changes every occurance of a
character as you require
Free space - tells you how many free bytes you have left
SPECIAL GRAPHICS ROUTINES
Hyper graphics mode -graphics never seen on a 2Х81
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First computer version of this popular
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Fill - fills your screen instantly with your ѕресі:.еа character
Reverse - changes each character on your screen to 15
inverse video
TAPE ROUTINE - provides a system WAIT condition
until a signal is received in the cassette ear Jack.
WORD PROCESSOR (IT WAS USED TO WRITE THIS AD)
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and gives running score
position of your fleet then locate and
destroy the computer s fleet. Visual
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All these routines are written in machine code and together
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22 exciting MACHINE CODE routines that give you control over your screen as never before!
Onscreen/Offscreen turns your screen on or off.
Background On/ Off Fills your screen by your
specified character. When foreground is on existing
information is unaffected and shapes will appear to
pass in front of your background, without deleting it
Search and Replace will search the screen for
every occurrence of the character you specify and
replace it with your new character.
Square draws a square or rectangle from your
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Your border is protected when foreground is on
SPECIFY ZX80-1 OR TRS 80 COLOR COMPUTER
ZX80-1'S NEED 16K RAM
TRS 80 NEEDS 16K RAM
video, control as in FILL
Print Position Controls
ОР. DOWN, LEFT, RIGHT - alter your next PRINT
position in the direction indicated
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Scroll facilities
PRINTER LEFTSCROLL - Scroll your screen in the direction
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Fill Fills any number of lines you specify, starting at
any line you specify, by your chosen character
Reverse Converts all characters to their inverse
UPSCROLL, DOWNSCROLL, RIGHTSCROLL,
specified co-ordinates.
All these routines are in machine code for SUPER-
FAST response! Simply load GRAPHICS
TOOLKIT, which repositions itself at the end of
your RAM, and then your own program (or key in a
new one), GRAPHICS TOOLKIT uses only 2K of
your RAM and that includes space to load the
programmers TOOLKIT described above.
ALL FOR ONLY $11.90 (£5.95)
This includes a cassette with 2 copies of the
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examples.
Editprint Moves next PRINT position to first edit line
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SYNC Magazine
34
% Жж
SEPTEMBER S FEATURE
PRODUCT
Quicksilva Sound Board
4096 seperate tones on each of 3 channels
Volume control of each channel
White noise generator with pitch control
Envelope shaping facilities
Two 8 bit in/out ports
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OTHER QUICKSILVA
PRODUCTS
QS Motherboard and QS Connector
Allows use of RAM pack and up to 2 add-on
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SV regulator cures overheating
сори and Motherboard plug into back
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Permits use of add-ons such as ©5 Sound
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QS Programmable Character Generator
QS мощотроса ....._..... SS $27.75
GS Connie. oie cae TL or eae $9.25
QS Hi-Res Graphics Controller
256 (horizontal) by 192 (vertical)
Has 2K of ROM and 6K of RAM — fully buffered
No software required
Easily connected to QS Motherboard
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QS Programmable Character Generator
Program up to 128 different characters at a
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Characters are stored in 1K of RAM on the
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Each character is built on an 8x8 square
No charge is necessary to existing programs
Operating cassette included
БОГ а А $49.50
QS 3K RAM Boards
Gives total of 4K of RAM
Does not suffer from “amnesia” and
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QS 3K RAM $34.75
Software
QS Harmony
А program designed to exploit the musical
potential of the QS Sound board ..... $8.95
QS Asteroids
2Х-81 + 4K RAM minimum ............ $9 95
QS Invaders
ZX-81 + 8K RAM minimum ............ $9 95
QS Defenders
ZX-80 or 81 8K ROM + 4K RAM minimum$9 95
АП QS software is recorded twice on quality
cassettes
All are written in machine code for fast
moving graphics
The programs have received very good ratings
JP GIBBONS
Personal Banking System
Single key operation
Search by check number, description or
amount
File can be displayed, printed, added to,
cancelled or amended
Validation of entries
Requires 16K and cassette
Personal Banking System ................ $19.95
MELBOURNE HOUSE
Not only 30 programs for
The Sinclar ива nuo $14.95
Machine language made simple ..... 19.95
ZX81 ROM Disassembly Part A & B$1495 each
(2 volumes) — Dr. Ian Logan
Understanding Your ZX81 ROM ........ 19.95
Dr. Ian Logan
The Sinclair ZX81 basic course ........ 35.00
Cassette Tapes
ZX Chess — 16K ZX80-8K/ZX81 24.50
10 Exciting Programs — 1K ZX81 1495
Adventure A — 16K ZX80-8K/XZ81 19.50
Adventure B — 16K ZX80-8K/ZX81 19.50
Adventure C — 16K ZX80-8K/ZX81 19.50
Spacetrek — 16K 2Х81 1495
Directory/Record — 1K ZX80-8K/ZX81 1495
with listing
Reversi — 1K ZX80-8K/ZX81 1495
Super Invasion — 1K ZX80-8K/ZX81 1495
Wallbusters — 1K ZX80-8K/ZX81 1495
ZX Galaxians — 16K ZX81 1495
ZX Bug Utility Program — 16K 7Х81 2450
If you are a producer of quality hardware or
software for Sinclair products and are interested
in having a US. or Westcoast organization
marketing your products we would like to hear
from you.
NO HANDLING OR SHIPPING CHARGES.
Washington residents add 6.5% sales tax.
P.O. Box 2288, Redmond, Washington 98052
being fairly quiet (ComputerTowns
please note). You can pick this sound
up from the cassette ports if you so
wish. l'd say these facilities are more
likely to be used for sound effects than
composing symphines.
That's really all I have to say about
the Basic. It is a very good implementa-
tion for a machine of this size. A
PAINT instruction would have been
nice to fill in graphics shapes, but I
think it would look a bit weird in multi-
colour mode with the colours changing
at each character boundary. A routine
to do this should be simple enough. I
think the screen resolution is quite ade-
quate for most personal users of the
machine. In fact you can churn out
some quite stunning effects using
DRAW, PLOT, CIRCLE and the user-
defined characters.
Before moving on to documentation,
here's a list of the disk commands just
to whet your appetite: CAT, CLOSE,
DELETE, ERASE, FORMAT, MOVE,
OPEN. CAT is probably short for
Catalogue which lists the files on a disk.
MOVE probably copies a file from one
place to another. The others are self-
exaplanatory.
Documentation
Two manuals come with the Spectrum
— a thin but useful introduction for the
complete novice and a thicker one
which explains things in depth. A lot
of effort has been put into this latter
manual. It is professionally presented
and easy to read. Unfortunately, I was
given a photocopy of the final proofs
and it contained no index and no table
of contents. I read the whole manual а
couple of times before starting the
review and I found it a real problem to
find things that I knew were there
somewhere. | must admit that the style
wasn't to my liking; it's a little verbose
and the individual chapters seem to lack
structure. I also found the inevitable
errors which might cause a beginner
ZX 80/81
16K RAM
— — —— Plug in and Run — ——
This RAM Memory Expansion
has a reliable, proven connector
and requires no additional power
other than that supplied by
the ZX 80/81.
What about the '81?
It was no secret that 'Uncle' Clive
was going to launch a knockout micro
— he's put a bomb under the industry
twice already, producing machines
which brought computing power with-
in everybody's reach at prices which
drastically undercut the competition.
problems — things like a minus sign
being printed instead of equals, for
example. The manual certainly seems
to cover everything, so if a table of
contents and a comprehensive index are
added you'll probably find it adequate.
It's certainly an improvement on many
manuals on the market.
Potential use
This is the first machine that I’ve
reviewed since the Atari two summers
ago that I would actually buy — in fact
I will have probably ordered one by the
time you read this. I would use it for
Fully tested with a 90 day warranty.
PROPOS TECHNOLOG
36
350 N. Lantana Ave., Suite 821
A slightly upmarket (by Sinclair
standards) machine offering colour
and sound and reasonable graphics at
a price far, far below that of any
equivalent machine was a logical step
to take, especially in view of Sinclair’s
obvious annoyance at being left out of
the BBC deal.
What is interesting, though, is that
the Spectrum does not replace the
ZX81, as the 81 did the 80 — it’s an
addition to the range and the ZX81
will continue in production. In fact,
production of the 81 is to be increa-
sed to a target of 150,000 a month by
the end of the year.
‘The ZX81 will continue to be ideal
for the person who wants the lowest
possible entry cost into computing,’
says Sinclair. And to prove the point,
he’s knocked £20 off the price of the
16k RAM pack. |
At the moment Spectrum is avail-
able only by mail order and is only
on sale in the UK — there are no plans
yet to market it through retail outlets,
as is done with the ZX81 through
W H Smith, and export versions are
not planned until the end of the year,
with the USA being the first (and
largest) market to get the new
machine.
Peter Rodwell
fun, for fooling around with graphics
and for programming in 280 code. I
would treat it as a hobby machine, a
way of relaxing. My children have
already become very interested in the
graphics capability and I see this as a
way of giving them a real understanding
of mathematics. A Logo system on this
at the right price would go down an
absolute treat — if anyone out there
thinks of doing it, I'd love to review it.
Of course, there are those who want
to learn to write programs. Once again,
this is an excellent machine to cut your
teeth on. I think that schools and
To Order:
Send Check or M.O.
$45.95 + $4.00 S & H
or Phone: 805/482-3604
Visa or M.C.
Cal. Residents Add 6% Sales Tax.
e Camarillo, CA 93010
SYNC Magazine
homes have got to be the prime targets
for Spectrum at the moment.
Later on when the disk drives appear,
this may change. At a predicted £50 for
a 100k drive, a lot of people who will
have written the Spectrum off as a
hobby machine will have to think again.
Add to that a £20 combined RS232
and communications facility, and you
could be talking about some very
interesting and fairly sophisticated net-
works. At that stage, it becomes a very
real prospect for schools looking for a
fairly grown-up system, but one which
can involve as many pupils as possible.
At Sinclair's prices could we possibly
be heading for the ‘one on every desk’
scenario painted by so many futurolo-
gists?
Until those disks arrive there is no
great office potential for the Spectrum.
Once they're on stream then it's pro-
bably just a question of appropriate
software. Information management and
Visicalc-type applications would seem
to be the most likely and, because of
the price of the television, they will
probably be used with portable black
and white machines. No doubt the
dedicated will take their Spectrums (or
is it Spectri?) home to plug into the
colour TV. Most people will probably
wait until Sinclair announces a flat
screen colour television. The network
idea could then be useful in offices for
things like telephone directories, notice-
boards and memos.
Prices (inc VAT)
Conclusions
Well, for the benefit of those who only
read the first and last paragraphs of
these reviews here are my conclusions:
Clive Sinclair has produced a very good
16k personal computer which offers
colour, high resolution graphics and
limited sound for just £125. That
represents very good value for
money provided that this is the sort of
machine you want, It is ideal for people
who want to learn about computing and
have a lot of fun while they're doing it.
Given the right sort of graphics-based
educational software, it сап bring
people very pleasurable ways of learning
subjects such as mathematics and
geography. Once the games programs
start to appear, a lot of people will use
it just for that, although it does seem a
bit of a waste.
Later on, the provision of disk drives
and communications facilities will make
it an even more serious contender for
the school markets and it will begin to
creep into businesses. When the flat
screen television appears then I suspect
that the business interest will rise
because the price will be far more
appropriate. Bulletin boards, memos,
telephone directories, spreadsheet cal-
culation and information management
seem to be the most likely applications.
The ‘proper’ keyboard is a distinct
improvement on its predecessors, but it
still doesn’t achieve — or try to achieve
— the quality of an IBM. All the old
regular Sinclair features are included —
the single keyword entry and the auto-
matic syntax checking as you enter each
command, for example.
My verdict? The best value for
money you can find today! a"
I would like to thank John Mathieson
of Sinclair Research for so patiently
answering my questions.
Benchmark timings
ВМ5
ВМ6
BM7
BM8
24.0
55.3
80.7
25.3
АП timings in seconds.
Technical data
16k Spectrum £125
48k Spectrum £115
32k Memory £60
Microdrive disk (estimated) £50
RS232 + Comms (estimated) £20
ZX Printer £59.95
BM1 4.8 BM3 21.1
BM2 8.7 BM4 20.4
CPU: 3.5 MHz Z80A
Memory:
Keyboard:
Auto-repeat
Screen:
Cassette: Domestic recorder.
Disk drives:
Ports:
Language: Basic in ROM
July/August 1982
16k Dynamic RAM, 16k ROM, 32k expansion option
40 keys rubber moulding. 183 functions + 8 colour labels.
Domestic colour television. 8 Colours or 6 grey shades.
To be announced. 100k per drive.
To be announced. RS232 & comms.
Sinware's
HOT Z
HOT Z is a program designed to give you
the control and understanding of your
computer's soft side that you will need to
get the most out of the new generation of
ZX equipment. Use it to manage the con-
tents of that 64K memory or to write I/O
routines for peripherals. Use it to under-
stand your ROM and get the best out of
your hardware, or to learn machine pro-
gramming, which is much less forbidding
when you have the power of HOT Z's 40
commands at your fingertips.
HOT Z provides:
Disassembly of Z80 code, floating-
point code, CHR$ code, with named
system variables and no warmed-
over 8080 jingo.
The ability to annotate your memory
with hundreds or thousands of labels
for better understanding of programs
and files. Full set of HOT Z labels
supplied.
Easy cursor-guided entry of machine
programs with instant disassembly of
each step.
Edit functions to insert, delete, trans-
fer, clear, search, load or save blocks
of memory.
e Single or multi-stepping of programs
anywhere in memory, even ROM or
above 32K, with full display of regist-
ers and flags.
e Smooth fast 24-line displays at all
times.
Instant access to command prompt
displays.
e 50 pages of instruction and docu-
mentation.
е An expandible system: Assembler
available soon.
HOT Z shares memory space with BASIC
programs, is stable, friendly, and re-
freshes the flip-flops that other programs
cannot reach. Special versions for 16K
RAM, 32K + RAM, 2Х80 or 81. Specify.
$19.95 ppd.
SINWARE
BOX 323, DIXON, NM 87527
37
8K ROM; 1K RAM
Double Your Memory
J. Wayne Schneider
Ed. —A WORD OF CAUTION: Апу
hardware project for your computer must
be approached with extreme caution.
SYNC cannot be responsible for any
problem that may arise from attempting
hardware projects. Obviously, any dam-
age to your computer can be costly in
time and money.
The first few days of working (playing?)
with a new Sinclair 2 Х81 are filled with
anticipation, excitement, and, for the kit
builder, triumph and pride. Seeing that
little black K on the screen when the
ZX81 is first powered up brings exclama-
tions of joy from the new programmer
and a questioning stare from uninitiated
bystanders. Alas, all of this excitement
soon dwindles into frustration with the
first attempt to impress a sceptic viewer
with a simple random graphics display.
There is not enough RAM for even one
full screen and a modest program.
Do not despair! There is a reasonably
quick and almost painless solution.
Although the ZX81 was designed to be
inexpensive, a foresighted designer has
provided the circuitry to use a 2K x 8 bit
static RAM on the circuit board. The
whole process involves removing the two
2114s at IC4a and IC4b, installing а 2K x
8 RAM at ICA, and adding a jumper at
L2. If you are lucky enough to have a
ZX81 with a 4118 RAM, you will not
even have to change IC sockets. Simply
remove the 4118, install the 4802 in its
place, and change the jumper at L1 to L2.
One warning for those with factory built
computers: performing the procedure
described here will void your warranty.
J. Wayne Schneider, 1601 South 450 West, Provo,
UT 84601.
38
Preparations
You will need a clean, dry workspace
at least two by four feet. The area should
be well-lighted and protected from solder
drippings. An old bath towel spread over
a table makes an excellent surface on
which to work, but make sure it is an
expendable towel before you burn a hole
in it with a hot soldering iron. Further-
more, it protects both the table and the
ZX81.
You will also need the following:
1) A light, 15-25 watt soldering iron
with a fine tip.
2) Fine gauge rosin core solder.
3) A pair of sharp wire cutters.
4) A Phillips screwdriver with a no. 1
point.
5) A 2K x 8 static RAM. These are
manufactured by several companies.
Mostek’s 4802 is no longer being manu-
factured, but it is still available from many
electronics supply stores. Mitsubishi
makes an equivalent part that costs less,
number M58725P. Hitachi’s CMOS part,
number 6116, which requires considerably
less power, is your best bet if you are
concerned about the ZX81 overheating.
Others are the Toshiba 2016, the Fujitsu
MB8128, and the NEC part 4016.
If your ZX81 has the two ICs labeled
uPD2114LC, you will need to buy a 24
pin DIP socket for the new RAM or else
two 12 pin SIP sockets. The DIP (dual
inline pin), socket is structurally better,
but the SIPs can be installed without
removing the old 18 pin socket. You will
need some solder wick to help with the
desoldering of the old 18 pin DIP socket
if you are going to add a 24 pin DIP
socket.
New rubber feet or glue will be needed
when you reattach the rubber feet to the
back cover of the ZX81.
When you have all of the parts and
about three hours to spare, you are ready
to begin.
Operations
Get all of the parts and tools together.
Disconnect the ZX81 from everything,
especially from the power supply. Place
it flat in front of you just as though you
were going to type on it.
1) Remove the back cover.
Turn the ZX81 over so that it is posi-
tioned as shown in Figure 1. There are
five screws to remove. Only two of them
are visible. The other three are under the
rubber feet at positions 1, 4, and 5.
Carefully remove the three rubber feet
and save them for later. If you are lucky,
the sticky will come with them, and they
can be stuck to a piece of wax paper for
installation later. Now remove all five
screws. Notice that screws 4 and 5 are
shorter. Set these in a safe place. Gently
lift or pry the back cover off. It should
come easily without forcing.
2) Remove the printed circuit board.
Remove the two screws that hold the
printed circuit board in place. Note their
exact position for reassembly. Very care-
fully lift the circuit board and rotate it
back towards you until it is face up. Be
extra careful not to stress or crimp the
flat tails connected to the keyboard. You
may now disconnect the keyboard by
pulling straight and steady on one tail at a
time. Set aside the cover with the key-
board attached.
3) Remove the existing IK RAM.
Turn the keyboard around 180 degrees
so that the flat square metal heat sink is
on the lower left as shown in Figure 2.
Remove the two 18 pin ICs at IC4a and
IC4b. These are the 2114 ІК x 4 Би
RAMs. If your ZX81 does not have these
two ICs, then it will have only one 24 pin
IC at IC4. Remove this IC. It isa 4118 1K
x 8 bit RAM. Save the RAM where it will
not be subject to extreme temperatures
or Static.
4) Install the new IC sockets.
If you are one of the lucky ones whose
ZX81 came with a 4118 RAM, you can
ignore this process. Otherwise, carry on.
Place the new sockets in the lower 12
holes on each side of location IC4. If the
SIPs do not fit easily into the holes or if
you are using a DIP socket, you will have
to desolder and remove the 18 pin DIP
socket. Now turn the board over and
solder the new socket in place. (Caution:
never bring a hot soldering iron close to a
chip or any other component. Be sure
that all the chips have been removed.) Be
careful with the solder. Use enough to fill
the hole but not so much that it runs
down the pins and shorts something out.
Turn the board back over.
SYNC Magazine
Figure 1: Bottom of the ZX81.
Figure 2: Board Orientation and IC Location.
(2)
9
bes cud
EE
Long screws
| "n
B
———À "lg
Sed
Se
Short screws ааа
5) Install a jumper at L2.
Those who have the 4118 RAM must
first desolder the jumper at L1. Use a
short piece of wire bent in a U shape to
connect the solder pads at L2. Solder it in
place. Be careful not to get too much
solder.
6) Install the new 2K RAM IC.
Place the new 2K RAM ш the new
socket. It should be oriented with pin 1 to
the upper left. Finding pin 1 may be a
problem. The IC will probably have a dot
etched or molded into the top surface
adjacent to pin 1. If you cannot find a
dot, there will be a notch in the center of
one end. The notch should face away
from you. If you had a 4118 RAM, be
sure you are installing into the lower 24
holes. Nothing goes into the upper four
holes. Push the socket into place. You
may find it necessary to bend the pins
inward to make it fit. After the IC is in
place, inspect it to be sure that all the
pins are in their holes and not bent
underneath the IC.
7) Reassemble the Z X61.
Turn the printed circuit board 180
degrees so that the square metal heat
sink is at the upper right. Place the cover
July/August 1982
vm. c NEL
beneath the circuit board. The keyboard
tails should form a graceful loop back
over the upper left corner and into their
sockets. Be very careful when pushing
these fragile tails into the sockets. If they
are bent or torn, you will not have much
success in getting the ZXS81 to work.
Rotate the circuit board back into place
in the cover. Check the keyboard tails for
positon. Screw the board in place with
two of the short screws at the positions
you noted in step 2. Replace the cover
and screw it down using the short screws
at locations 4 and 5. Do not use the long
screws in the wrong place. You could
damage the keyboard. Glue the rubber
feet into place. When you install the
rubber feet, place them to the side of the
screw holes, and you will never have to
go through that misery again.
Trouble
Connect your ZX81 to your TV again
and plug in the power. If it works, treat
yourself. If not, check the solder joints.
You may have to resolder them. Do not
resolder with the IC in the socket. Check
the IC for orientation. Be sure all of the
pins are in the holes. Did you forget the
Metal heat sink
jumper? If the computer displays the
inverse K but will not respond to the
keyboard, check the tails. They should
be seated straight in their sockets. The
fault rarely lies within the RAM IC itself.
However, that is a possibility. At that
point you will need someone experienced
in working with digital circuits to. help
you solve the problem.
Conclusion
Now that you are up and running, try
the following command:
PRINT PEEK 16389*256-16384
That should display 2048, which is the
amount of memory you now have avail-
able. A full screen requires 704 bytes of
memory. The system variables require 125
bytes. With 1K of RAM, you are left with
195 bytes for a program. With 2K of RAM
you are left with 1219 bytes; over six
times as much program space. Of course,
the ZX81 Basic does not really dedicate
704 bytes of memory unless your program
fills the thirty-second position of every
line. That will rarely happen, but now
you can enter a reasonably long program
and still have a full screen display if you
want it.
39
GAMES PALKS
for 1K ZX81 в 8K ROM 7Х80. Eight
fantastic programs for the
unexpanded 2Х81, includin
DIGICLOCK, 9-LIVES, REACTION TEST;
GOBBLER and PATTERNS.
$9.95 ($12.95 in Canada)
for 16K ZX81. Four programs writ-
ten in BASIC for the expanded
ZX81. PONTOON, FRUIT
MACHINE, OXO, and BIO— RHYTHMS.
$9.95 ($12.95 in Canada)
З
for 16K ZX81 and ВК ROM 2Х80.
Two programs for expanded ZX81
to keep you entertained for hours!
3-D OXO is written in machine code and is
hard to beat. MARS RESCUE is a com-
pulsive adventure game.
$9.95 ($12.95 in Canada)
for 16K ZX81. ZOMBIES — escape
as they chase you around Zombie
Island. Lure them into the pits, but
4
don't fall in yourself. MOUNT MAYHEM —
can you reach the 20,000 foot summit?
Look out for Yetis and other hazards!
$9.95 ($12.95 in Canada)
DICTATOR
Fantastic new adventure game for 16K (or
greater) ZX81. You have just become 129th
ruler of Ritimba with a single goal in mind:
take full advantage of the situation for
your own good. You have to deal with a
handful of factions: unruly army,
downtrodden peasants — but you have
the secret police on your side.
$14.95 ($17.95 in Canada)
Turn your ZX81 into a telescope with this
amazing 16K program. Produces a simula-
tion of the night sky as seen from any
position on Earth at any chosen time this
century. You may point your telescope in
any direction, move it up, down, left or
right, zoom in or out. Stars may be
displayed by magnitude or constellation
$14.95 ($19.95 in Canada)
CHESS
A challenging chess programme, written
in machine language, designed to operate
in the ZX81 fast mode. ZX Chess allows
you to select from 6 levels of play, choose
either black or white, and enables castlin
and en passant moves. Unique ‘‘self-
running” feature: you start the tape and
when the chess board appears on the
screen, start your game.
fe, CHESS! NOW $42.95
CONSTELLATION
Machine Code Disassembler
ZXAS Nasce
Now you can use the full power of the Z80
microprocessor without having to
laboriously POKE in instruction codes.
This full specification 280 assembler
assembles all the standard Zilog
mnemonics, which are simply written into
REM statements (more than one per lineis
allowed) within your BASIC program.
When assembled, the assembly listings,
together with assembled codes and
adresses, are displayed on the screen.
The assembled code is executed by USR.
The program occupies 5K, is situated at
the top of the memory, and is protected
from overwriting. This means that ZXAS
may be used in conjunction with ZXDB
(see below), providing an extremely power-
ful machine code system normally only
found on very expensive computers.
The program is available for both the ZX81
and the 8K ROM ZX80, and in both cases,
the 16K RAM pack is required. Despite the
low price, ZXAS is. а FULL-
SPECIFICATION assembler, and is a must
for all serious ZX users. Full documenta-
tion on how to use the assembler (in-
cluding a list of the mnemonics) is sup-
plied.
59. 95 ($12.95 in Canada)
ZXD Debugger
The perfect complement to tne ZXAS
assembler, ZXDB is a complete combined
machine code disassembler and debugg-
ing program. Like ZXAS, it is itself written
in machine code for compactness, and
may be used in conjunction with ZXAS,
still leaving about 9K of memory for your
Own program.
Apart from the DIASSEMBLER, the pro-
gram has features including SINGLE
STEP, BLOCK SEARCH, TRANSFER AND
FILL, HEX LOADER, REGISTER DISPLAY
and more, all of which are executed by
simple one key commands from the
keyboard. All in all, an extremely powerful
programming aid, well worth the money
for the disassembler alone!
$9.95 ($12.95 in Canada)
STAR TREK
The classic computer game in which you
trek across the galaxy in search of КІ-
ingons to zap with your phasers and
photon torpedoes. You have long and
short range scanners to help you find
them, Starbases to refuel your ship at and,
of course, various witty comments from
the crew. 16K.
$9.95 ($12.95 in Canada)
Disassembler/
VU-CALC
VU-CALC. Constructs, generates, and
calculates large tables for analysis,
budget sheets and projections. Up to 26
columns of figures or data can be entered,
plus user definable formulae capable of
relating any one or more position in the
table to any other defined position.
NOW $14.95
MULT IF па e
PROGRAM С) 1981 сес-стте
SET UP FILE PARAMETERS
SUM en FILE
SECURITY LOC
SAVE FILES ON TAPE
1
з
з
4
5
6
?
з
ENTER YOUR CHOICE (1-3)
MULTIFILE
rele Storage System
An amazingly versatile multi-purpose fil-
ing system for the 16K ZX81. The program
is menu-driven, and number, size and
headings of files are user-definable. Both
string and numerical files are catered for.
Files may be created, modified, replaced,
and searched, and are protected by an in-
genious foolproof security system. Out-
put to the ZX printer is also provided. The
program comes on cassette, together with
three quality data cassettes for file
storage, and comprehensive documenta-
tion, describing a host of applications for
both business and personal use. Supplied
in an attractive storage case. If your ZX81
is bored with playing games, then this pro-
gram will give it plenty to think about!
$29.95 ($39.95 in Canada)
New Multifile Plus for 64 K RAM $34.95
VIEWTEXT
A ten page information display system for
the 16K ZX81. Can display both text and
graphics in any sequence with variable
speed. Many applications including shop
window displays, educations, animation,
etc.
$14.95 ($17.95 in Canada)
Gladstone Electronics, 901 Furhmann Blvd., Buffalo, N.Y. 14203 (716) 849-0735
Atlast, a comprehensive text for your Sinclair ZX 81!
The complete BASIC Course is a manual which will
immediately become an indispensible work of
reference for all your ZX 81 programming.
Whether you have never done any programming or
whether you are an experienced microcomputer
user, the Complete BASIC Course will provide itself
to you as an invaluable aid.
The Complete BASIC Course is designed to teach
you to write and develop BASIC programs for the
Sinclair ZX 81 - no other books or aids are
necessary. All is revealed in our easy step-by-step
guide with programs and "test yourself" exercises all
the way through.
As you become more proficient with computing, the
Complete BASIC Course will continue to be an
essential guide, giving you finger tip references,
numerous advanced programming techniques and
memory saving devices specifically for the Sinclair
ZX 81.
HOW TO WRITE PROGRAMS:
Even if the idea of writing programs is completely
mystifying to you, the Complete BASIC Course will
show you just how easy it is. In no time you will be
able to write and enjoy complex programs for
whatever use you desire.
Using the proven "TOP-DOWN" approach, the
Complete BASIC Course will show you systematic
and simple ways to write programs. Even
experienced programmers will benefit from this
Course, making programs easier to write and less
prone to error!
NUMEROUS EXAMPLES:
Every concept, every function is fully described by
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Part 3
Understanding Floating-Point
Arithmetic
In this article on floating-point arith-
metic we will consider the algorithms that
are used in the 8K ROM program to
perform the operations of subtraction,
addition, multiplication, and division. The
8K ROM program has four separate
subroutines for performing these arith-
metic operations. The hex addresses of
their entry points in the ВК ROM
(improved) are:
Subtraction: 174C
Addition: 1755
Multiplication: 17C6
Division: 1882
In each case the subroutine performs
its operation on the top two floating-point
numbers found on the "calculator stack,"
and returns the result as a single floating-
point number that replaces the "lower" of
the two operands. The pointer to the end
of the calculator stack (STKEND) will
point five locations lower after each
operation in consequence.
Now, before going into the details of
these four subroutines, let me recap how
a floating-point representation of a deci-
mal number is produced.
In the ZX80/81 system floating-point
numbers occupy five bytes. The exponent
takes one byte, and the mantissa, four.
The first stage, therefore, is to consider
your decimal number in E format. It is a
convention that the mantissa has only a
fractional part and thereby starts with a
decimal point. To illustrate the process
let us take the number 456.
The decimal exponent will be +3, and
the decimal mantissa will be .456. Note
that the number is positive.
Next the operations should be repeated
in binary to obtain a "true" binary floating
point. The binary representation of 456 is
1 1100 1000. The exponent is +9 or 1001
and the mantissa will be 1110 0100 O.....
Dr. Ian S. Logan, 24, Nurses Lane, Skellingthorpe
Linclon, LN6 OTT, U.K.
July/August 1982
lan S. Logan
Now the exponent and mantissa can be
made up to the correct size and expressed
in hex as follows:
Exponent: 09 (1 byte)
Mantissa: E4 00 00 00 (4 bytes)
To obtain the correct Sinclair repre-
sentation there are two further conven-
tions to follow:
1) Add 128d (80h) to the exponent.
2) Replace the first bit of the mantissa —
it is always set! — with a zero if the number
is positive.
Hence, the final representation for 456
will be:
89 64 00 00 00 in hex, or
137, 100, 0, 0, біп decimal.
Now let us consider the actual sub-
routines.
Subtraction
The subroutine that is uniquely used
for the operation of subtraction is very
short as the algorithm used is to change
the sign of the subtrahend (the number
being subtracted) and then to proceed
with an addition. The actual steps are:
1) Fetch the subtrahend and return if it
has the value 0; i.e., 456 - 0 is always 456
and the operation of subtracting a zero
can be ignored in all cases.
2) Fetch the first byte of the mantissa
of the subtrahend and "flip" the sign
bit—the first bit: 456-315 = 456 + (-315).
3) Proceed to add the two numbers.
Addition
This subroutine is fairly complicated as
it has to cater for simple additions of
positive numbers whose results are
“within range,” for additions with negative
numbers, and for additions that go "out
of range."
The essential parts of the subroutine
are, however, fairly easy to explain. The
steps are:
1) Fetch the augend (the first number
of the addition). Reduce the exponent by
80h, restore bit 1 of the mantissa if the
number is positive and make a note of the
sign of the number. The augend is now in
a "true" floating-point form.
2) Fetch the addend (the second num-
ber of the addition) and produce its "true"
floating point form.
3) Compare the "true" exponents
against each other and, if the addend is
larger than the augend, switch over the
numbers. I.e., when adding 456 + 38, the
exponents in decimal are +3 and +2, so
leave as is. But, when adding 38 + 456,
switch over the numbers to make 456 +
38.
4) Find the “difference” between the
exponents. This difference is the “amount
of shift” that will be needed to “line up”
the addend for the actual addition. This
can be shown in decimal as follows:
456 + 38 is (.456 E + 3) + (.38 E + 2)
The difference in the exponents is +1,
and the addend is shifted one place to the
right to make the addition:
(.456 E + 3) + (.038 E + 3)
Now the true addition takes place
between the mantissas, and the result is
(456 + .038) Е + 3 = .494 E + 3 = 494
5) Therefore shift the addend right-
wards if needed and add the two numbers
—the mantissas—together.
6) Normalize the result if it is not
normal. |
In binary floating-point the above addi-
tion of 456 + 38 becomes:
456 is 137, 100, 0, 0, 0
with a "true" form of 9, 228,0,0,0
38 is 134, 24, 0, 0, 0
with a "true" form of 6, 152, 0, 0, 0
The augend is larger than the addend so
the numbers do not need to be switched
over, but there is a “difference” of +3, so
the addend has to be shifted three places
to the right to line it up with the augend.
Thus
456 stays as 9, 228, 0, 0, 0
whilst 38 becomes 9, 19, 0,0,0
The two mantissas can now be simply
added together to give the result
456 + 38 = 494 as 9, 247, 0, 0, 0
This result does not change with nor-
malization but with the exponent aug-
mented and the sign byte entered it
becomes finally:
494 is 137, 119, 0, 0, 0
Note that, when an addition involves
negative numbers, the subroutine 2's
complements the negative mantissas, and
that, if the final result is to be negative, it
too will need to be complemented before
being placed on the "calculator stack."
Multiplication
The subroutine for multiplication is
fairly straightforward. For two numbers
in floating-point form to be multiplied
together, the exponents are simply added,
and the bytes of the "true" mantissa are
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multiplied together bit-by-bit. The man-
tissas, being "fractional," when multiplied
together, decrease in absolute magnitude
and hence there is no danger of overflow.
However, the addition of the exponents
has to be checked for all the instances of
“underflow” — reaching zero—and true
numeric overflow.
The actual steps of the subroutine are
as follows:
1) Fetch the multiplier (the first number
of the multiplication) and return if it is
already 0; if it is not, form the “true”
mantissa.
2) Fetch the multiplicand (the second
number of the multiplication) and force
the result to be 0 if it is already 0. If not,
again form a “true” mantissa.
3) Make available a set of registers to
hold the result of the multiplication and
set a counter to count the 32 times
required for the multiplication of a pair
of 32-bit mantissas.
4) Perform the 32 operations that pro-
duce the result.
5) Add the exponents, check for
“underflow” and “overflow,” and finally
normalize the result.
As before, the algorithm will now be
illustrated with decimal numbers before a
binary example is given. Consider the
multiplication of 13 * 12 to give 156. When
converted to normalized E format, the
problem becomes
(13Е+2)“ (.12 E+2) equals (.156 E+3)
How is it done? Following step 3 above,
the result is set to be 0, and a counter set
for the number of digits in the mantissas—
in this case, 2. Then the following looping
is performed the specified number of
times.
The steps of the loop are:
1) Shift the multiplier rightwards and
note the carry.
2) Increase the result by the product of
the carry and the multiplicand.
3) Decrease the result by shifting it one
place to the right.
Now let us look at the example values:
1st loop
1) .13 becomes .01 with a carry of 3.
2) The result, presently 0.0, is increased
by 3 * .12 to become .36.
3) Decrease the result, by shifting right-
ward, to make .036.
2nd loop
1) .01 becomes .00 with a carry of 1.
2) The result, presently .036, is
increased by 1 * .12 to become .156.
3) Decrease the result, by shifting
rightwards, to make .0156.
This value of .0156 is the mantissa that
goes with the exponent obtained by
adding the “true” exponents, and the
result is presently 0.156 E + 4 which
upon normalization becomes .156 E + 3
which is the expected result.
In binary floating point 13 * 12
becomes
(132, 80, 0, 0, 0) * (132, 64, 0, 0, 0)
with the result 156 being 136, 28, 0, 0, 0
The “true” exponents of both 12 and
13 are 4, and the first nibbles (the first
four bits) of the “true” mantissas are
13: the bits 1101
12: the bits 1100
In this example for simplicity the multi-
plication will be made between two 4-bit
mantissas to produce an 8-bit result. The
full operation is 32 bits by 32 bits.
Now let us consider the loops.
Ist loop
1) The multiplier, 1101, is shifted to the
right to give 0110 and the carry equals 1.
1.
2) The result goes from 0000 to 1100
and is itself shifted to give 0110.
3) The end multiplier bit was set, so the
present multiplicand was added to the
result before it was shifted.
2nd loop
1) The multiplier goes from 0110 to
0011.
2) There is no addition of the multipli-
cand, but the result is still shifted to give
00110.
3rd loop
1) The multiplier goes from 0011 to
0001.
2) The result is increased by adding the
multiplicand; 00110 becomes 11110.
3) This is shifted to become 011110.
4th loop
1) The multiplier goes from 0001 to
0000.
2) The result goes from 011110 to
1.00111.
3) When shifted, it becomes 10011100
(8 bits given).
The exponents are now added and the
5-byte "true" number is formed as
8, 156, 0, 0, 0
which, with the exponent augmented and
the sign bit reset, is
136, 28, 0, 0, 0
and that is the floating-point representa-
tion of 156.
Division
Of all the arithmetic subroutines, divi-
sion is the most complicated and the least
understood. It is particularly interesting
SYNC Magazine
to note that the Sinclair programmer
himself has made a mistake in his pro-
gramming (or has copied over someone
else's mistake!) for
PRINT PEEK 60352 (“unimproved”
ROM, 6351)
should give 218, not 225.
To divide one number into another in
floating-point form requires subtracting
the exponents and dividing the mantissas
bit-by-bit. Care must be taken to get the
correct exponent for the result because
there is a "borrow" to be taken into con-
sideration.
The actual steps of the subroutine are
as follows:
1) Fetch the divisor (the second number
of the division) and give REPORT-6 if it
is 0; otherwise, form the "true" floating-
point form.
2) Fetch the dividend (the first number
of the division) and form its "true"
floating-point form. A return is made if
the dividend is 0 as there is no need to
divide into 0.
3) Set a counter to the number of bits
in the mantissas. In the actual 8K ROM
program the counter is used for 34 loops
as extra accuracy is sought — but then lost
because of the "programming error."
4) Perform the looping operation.
5) Subtract the exponents and adjust
for the "borrow" before, finally, normal-
izing the result as usual.
As before, the operation will be illu-
strated in decimal and binary arithmetic.
Consider the division of 486 by 3 to give
162 which, when converted to E format,
is (.486 E + 3/(L3E t 1) = .162E +3
So, the steps are:
First, set a counter to 3 as there are
three significant figures in the dividend.
. Second, perform the following division
loop three times:
a) Subtract the divisor from the present
dividend. If it does “ро,” count the times
that it does and proceed. Else, restore the
dividend and proceed with the count at 0.
b) Rotate the "times count" leftwards
into the result, initially 0.
c) Shift the present dividend also left-
wards and note carefully whether or not
a carry is produced. If there is no carry,
go to 1 on the next loop; but, if there is
carry, then the divisor will definitely "go"
into the dividend, and this is done directly
before going to 2 for the next loop.
Now let us see the example values.
Ist loop
1) .486 - .3 does go once, so make the
subtraction to give a new dividend of .186
and a "times count” of 1.
2) Make the result 1.
3) Shift the dividend leftwards and note
that there is carry.
July/August 1982
2nd loop
1) The divisor is now subtracted as
many times as it will go; i.e., 1.86 — .3
can be done 6 times and the dividend
becomes .06. |
2) The "times count" of 6 is rotated
into the result which goes from 1 to 16.
3) The dividend is now shifted left-
wards, with .06 going to .6 with no carry.
3rd loop
1) The present dividend is divided by
the divisor, giving a "times count" of 2.
2) This “times count" is then rotated
into the result which thereby goes from
16 to 162. Strictly, this should now be
read as .162. |
The exponents of +3 and +1 can now
be subtracted from each other to give
t2, the "borrow" taken into consideration
to make it +3, and the final result consid-
ered as .162 Е + 3.
Certain of the above mechanisms are
difficult to explain in decimal arithmetic,
but, by repeating the operation in binary
floating-point arithmetic, I hope these
points will become clear.
In binary floating-point the operation
is 486 / 3 or
(137, 115, 0, 0, 0) / (130, 64, 0, 0, 0)
with the result 162 being 136, 34, 0, 0, 0.
The “true” exponent for 486 is 9 and for 3
it is 2. In this case the division simplifies
to .1111 0011 / .1100 0000
and there will be eight loops to consider.
Ist loop
1) Trial subtract the divisor. It does go
once so the dividend becomes .0011
0011.
2) The "times count" goes into the
result to make it .0000 0001 and the
dividend is rotated to give .0110 0110.
2nd loop
1) The subtraction does not go.
2) So the result becomes .0000 0010
and the dividend .1100 1100.
3rd loop
1) The subtraction goes, giving a divi-
dend of .0000 1100.
2) The result becomes .0000 0101 and
the dividend is shifted to give .0001 1000.
4th-6th loops
1) On no loop does the subtraction
"go."
2) Hence the result becomes .0010 1000
and the dividend is .1100 0000.
7th loop
1) The subtraction goes, leaving a
dividend of 0.
2) The result becomes .0101 0001.
8th loop
1) The result still has to be shifted,
although the dividend has been
exhausted.
2) It becomes finally .1010 0010.
The exponents are now subtracted: 9 -
2 = 7. The ‘borrow” is considered to give
a final exponent of 8 and this makes the
result:
“true”: 8, 162, 0,0,0
in Sinclair form: 136, 34, 0, 0,0
which is decimal 162.
The reader is encouraged to try the
operations for any other values. Further
details of the arithmetic routines can be
found in Sinclair ZX81 ROM Dis-
assembly, Part B by Dr. Ian Logan and
Dr. Frank O'Hara. (Ed.— This work is
available from several sources. See the
ads in this issue.)
CHIRPER module for your ZX81
The CHIRPER module lets you enter keyboard
data fast and accurately. A sound can be heard
when a key has been entered enabling you to
spot a double entry or missed entry without
looking up at the screen.
The CHIRPER module lets you hear sound
patterns of a program running. Sound effects
can be created. Included is a program that plays
a tune of random notes on 1K or 2K machines.
The CHIRPER module installs easily inside the
ZX81 case with only З wires to connect. Com-
plete installation instructions included.
To order your CHIRPER send a check or
money order. We pay the postage in the U.S.A.,
elsewhere include first class postage for three
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MATRIX PLANNER-16K
An "electronic spreadsheet"
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Hardware required: 16K
SPACE INTRUDERS-16K
Play the world famous
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ADVANCED MACHINE
CODE MONITOR-16K
Here is the tool to help you
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4K ROM; 16K RAM
8K ROM; 16K RAM
ZX Destroyer
Raymond Fowkes
ZX Destroyer is a fast moving action
game which is written in a hybrid Basic/
machine language program to create a
continuous, flicker free display. The
machine language code routine is a care-
fully synchronized program loop which
controls the laser base, alien ship, and
video display. The Basic section provides
the initial set-up and ending.
4K ROM Version
Loading the Machine Code
The machine code routine is placed in
a REMark statement at the beginning of
the program. Remember, whenever you
are working with machine code, save
frequently. It is hard to save too often!
1) Type in the lines in Figure 1 very
carefully. Just enter the numbers one after
another. Do not enter the spaces; these
are included only for your convenience.
Note also that the O's in lines 1 and 2 are
not zeros. It is suggested that you SAVE
after entering each REM line.
2) Type in the checker routine in Figure
3) Press RUN and NEWLINE and wait
for the results.
4) Unless you are one of the lucky few,
the computer will indicate a mistake in
one of the four REM lines. If so, go back
and recheck your entry. Correct the
indicated line. Repeat this procedure until
the result is "PROGRAM OK." SAVE
the corrected version. You are now about
90% sure that the machine code routine
will run correctly.
Raymond Fowkes, PO Box 336, СоаПпра, СА
93210.
48
LASER 4
5) Enter the lines in Figure 3 over the
existing ones and RUN. The machine
code program has now been processed
and stored in line 1. Do not L/ST line l or
press HOME! Doing so could crash the
program and ruin all the work you have
just done. SAVE.
Entering the Basic Program
1) Erase lines 2-120 by entering the line
number and hitting NEWLINE.
2) Enter the program in Figure 4 exactly
as printed. This provides the set-up for
the game. SAVE again.
3) Press RUN and NEWLINE.
4) In the center of your display you
should see the alien space ship with the
alien in the middle of his control dome.
Two powerful rotating screens protect
the bottom of the ship. You will also see
the invader's laser moving back and forth
underneath the ship. It will fire when your
laser base comes into range.
5) In the lower left corner of the display
you will see a “$” which represents one of
your laser bases. In the upper left corner
the display will tell you how many func-
tioning lasers you have.
6) If the screen display does not match
the description in 4) and 5) above, go
back and check your Basic program or
reenter your machine code routine. If
neither of these works, wait for the next
Glitchoidz report!
8K ROM Version
The 8K ROM version is very similar to
the 4K ROM version and gives flicker
free action in the FAST mode.
Loading the Machine Code
1) Load the the machine code in Figure
6 as in step 1 in "Loading the Machine
Code" above. This code is a modification
of the 4K ROM version. Unlike the 4K
machine the 8K machine allows you to
LIST the REM lines without crashing the
system.
2) Enter the checker program in Figure
7. RUN the program in FAST mode.
3) After several seconds of processing,
the computer will indicate à PROGRAM
OK" or a mistake in one of the first four
lines. If you have 2K RAM, editing
requires a special process. First, LIST the
line with the mistake. Then execute a
CLEAR command and EDIT when the
screen is cleared. You can then make the
correction and return the line to the
program by pressing NEWLINE. RUN
again and make any further corrections
needed until the result is "PROGRAM
OK."
4) Enter the lines in Figure 8 over the
existing lines. SAVE. |
5) RUN the program. When it is fin-
ished, the machine code routine will be
processed and stored in line 1.
6) Delete lines 20-90 by entering the
line numbers and NEWLINE. Then enter
the lines in Figure 9. Line 10 causes CLS
to fill the screen with spaces. If you have
16K RAM, this is automatic, and you can
use this line as a place for the program
name. Lines 100-170 set up the display.
Lines 180-200 reset the laser indicators
and start the laser base at the lower left
corner of the display. Lines 210 and 240
should be entered only if your computer
can run in the SLOW mode.
7) Again SAVE. Then RUN. You
should see the same screen display as
above in the 4K version.
SYNC Magazine
Figure 1: 4K ROM Machine Code.
1 REM G41 923 111 117 CY9 U2A $47 38р UTS FXV
225 N59
СМ
FWV 22S NAA WYS
22C F1C 94C P57 28D
T1T 195 DQG 75Х BCM 55Ү
QA43 500 YCS BAL ска 2582
DEV -IYI SFU GOL- JET JMX
S6D-UAJ STG- СУ ЗАК EO?
MAA 9СМ
1T9
UAK
Job FTL СИМО
ETK QHR СЕ» K3Q
CF5 729 A9C МАТ 3X3 CDT
C44
5HA
121
ASE 7EG
SFC G37 LXG
QS6 DUA ZFU K37
38C. K63: X81
CK3 08
2 НЕМ FUL: САР 7WK ILE Url BLS 271. СОЗ ХМ? LEK
48H UK1 IEB
с62 MES H7L CGB 615 EZK
978 VAK 1@H 789 127 2Х4
ZHU K77 РОН АСТ 679 Х20
2JI 41Q Моро ?ВЕ
528 TIX ОКО 197. кота?
31H А1С G36
453 71
жей»
CXB 2с6
КС?
ACr
IV1
G
NK 771
KEH ACM
672 HUC IBS 97N
PHK 1CK 31r
643 IEB 956 DUA
101 QMF 012 015
Ври ЭК! 111 9517
бнс FÓL FU
5. ВЕМ 211.116 411-114 арин 231 41071-2581 16
152
121
1-72
121
141
171
612 478
317.311
111 17^
PPS 721
179.176
646: 112
212. 116
197 ir
212 426
716 576
111. 287
212 216
612
474
526
211
113
731
225 4 7.1 51
019: 460 351
144
ITE T73
116-711
118217 Би
741
741
221
412 12?
144 741
317-416 311
1231-1227 94T
139759415 11
111 721 42
211
211
515
Ш AGN. 231 LBT- 112/112 211 212-512 761. 171.27?
867
212
182
211
111
631
612
111
111
(14
433
ы
178
111
111
рай
111
731
rti
521
РЕ
122
611
114
292 291
2515-24 9
861 631
872 113
215 761
651 121
— Figure 2: 4K ROM Checker Program...
10 LET БО
20 FOR A=16426 TO 17419
зо LET В-В+РЕЕК (а) -РЕЕК (А+ 1)
40 ТЕ 4-166772 THEN IF NOT B=36
© THEN GOTO 120
SO IF @=16920 THEN IF NOT В=65
THEN GOTO 120
60 IF 217170 THEN IF NOT B=35
9 THEN GOTO 120
70 LET A=At1
Во NEXT A
90 IF NOT B=22 THEN GOTO 120
100 PRINT “PROGRAM ОК"
110 STOF
120 PRINT "MISTAKE IN LINE#";A/
249-65
July/August 1982
Ter 116-271
7563 1299 Iit
72117 12
211 21? 191
Ova ag NE
111 211 874
10
726)
ЗО FOKE A, PEEK (В) +РЕЕК (+498) Ж
22?
192 199
178.123
193 331 112
121-111 163
147 416 22
212 11
ELI
121
га
Figure 3.
LET B=16427
FOR 8-16427 ТО 16916
359-1044
40
BO
60)
7Q
во
90
100
110
120
LET B-E-1
IF B=16672 THEN LET B=B+4
NEXT A
PORE At3, 254
FORE At2,2
FOEKE At1,©
FOKE A,118
FORE 16403,2
LIST 2
____ Figure 4: 4K ROM Basic Ргоргат. о
100 РОКЕ 16421,24
110 FRINT "“LASER#S########WW "
120 LET BS=CHRS (121)
150 PRINT , "ЖЫНЫ"; Bo; вер HH" Е
: 2-02: Sp ae
140 FRINT
р"
150 PRINT ‚"#ЕЕ",""#####ЕКО"
160 FRINT ,„обавеня"; CHRS (128);
"онянен"; СНКЪ (156)
170 LET Bt=CHR$ (120)
180 FRINT ,EB$;"4S4443 48"; CHRE (154
);"ESHHHHHQ"
190 FRINT „РОЗ#Е#ЯЕ"; СНКЪ (154);
CHR$(126);"HHHHHH'":ES$
200 FRINT ,"QHHHHHHODHHHHHUH "у БФ
‚"Н#ННАРАЛАЛАЛААААААЛААААААЯААЯ",
"#НННАААААААААААААААААВАЛААААА",
210 FOR А=1 TO 14
220 PRINT
250 NEXT A
240 FRINT
290 Р ПЕ ЯЗЬ, О
260 РОКЕ.16452,177
270 FOKE 16457, 0
280 RANDOMISE USR(164 439)
200 INFUT At
2410 Ci
AGO RUN
"ЕНЕ Въ, "HH" LES LU
939 3 uN
— — Figure 5: Sample Opening and Ending.
159
во PRINT
AQ FRINT
до FRINT
во PRINT "SKILL: ##30=HEGINNER#
TO 1=EXFERT"
во INFUT я
70 IF ій OR А>20 THEN GOTO 60
go РОКЕ 16428, Å
Жос Саб
зоо IF РЕЕК(16427)-16 THEN GOTO
240
ath SOLS
220 PRINT "YOU WERE DESTROYED"
го GOTO 400
240 INFUT ES
ЖОО COLS
A60 FRINT
x"
A70 PRINT
380 ЕКІМТ
SOD PRINT.
TL
400 FRINT
410 FRINT
420 FRINT
420
440
4 NEN
"ЖЯТМУРОЕК DESTROYED#
"CRASH CURSOR"
"WOULD BE FROUD OF YO
"N/L TO FLAY AGAIN"
INFUT BS
IF E$-"" THEN RUN
(or THEN RUN 90)
Note: To make winning more difficult,
add this and delete line 70 (to prevent
memory overflow):
210 FOR й=1 TO 52
220 PRINT "++ ++ ++ ++“;
235 FRINT
49
Figure 6: 8K ROM Machine Code.
i REM G41nR82E111121?CYQU2BODUTZO
эцрвтиузаазоәзимоиуззгомиаззми?з5сманяыу
SHMRASCNSISAF #1 РТС х4асмеасе1се4 сЕ
ST2S5DUHKITOETKOHRCFA4HKOGTITIGOSDG:
гоъхвсмъзусез?гевнесматахзооптсхаао
ЭЭССБХТСКЗ=42С 64 тузазверрт ни шкв?::
PPIYVviSUURCISGCTS3HXRSE7TEGKOXMKCKGE
YSISODURJSTGGO74HRSFCGS3G7LXGCK30
e REM SULICHG7UKIZUUPIK15271C
G3GXUTICKS3IHRICGBO4SYUKTIIEBOSOT7T:!
GTZYUCIBS77NGOZHMPSH7LCGBOISE?KCG
SHNE27?7IPHKICKBIPO7RUSGKIQH7ROST27;
x*SCKG2C6646 LEBOSSHUAZYUKS?7PSHACL
CFSXVSCKC PEDUTESPOMFOLSOLSAUIXAAQHE
27781741514121272114741274173173
11121212162361144741211626212426
31117417274111131741531161531171
657?761157?721121?41111173121142211:5
132111242172176141221116211177217
ill73121221675111582176111117214
38 REM 242143811121142112125127
S1171272111586 7612324221178121116
aa id2721211162121211176121211176
22221111221 72111215351821118616312
117211741201780173121142211111972
11312721121211114:132111751111143
32112611118?731182121211111531115
31111565611217311112118741474165652
Figure 7: 8K ROM Checker Program.
58 LET В=@
ва FOR Я=16509 TO 17516 STEP 2
те LET В=В+РЕЕК Аж (PEEK (8 +1) -
ве LET C=(A-16507) 7126
90 ir C=2 AND B«i»2435229 O
AND B<>48894@ OR C=6 AND B
ваз THEN GOTO 148
ләә NEXT Я
110 IF Б%>733561 THEN GOTO 148
120 PRINT “PROGRAM OK"
зе STOP
1498 PRINT “MISTAKE IN LINE ";"i
2 геза“ (C-1 TO с)
Figure 8.
78 FOR A=B TO 17885 К
ва IF B-16768 THEN LET B-B46
PORE Я.РЕЕК В+РЕЕК (R4504) 4
18@ POKE 4.2132.
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SPECIFICA TIONS
Contact resistance: 200 Ф 1mA
Contact rating: 1.0V/A
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Switch life: 5.0x10® operations
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"Illinois residents include
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PRICE QTY. AMT.
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Figure 9: 8K ROM Basic Program.
ig РОКЕ 16389, 125
CLS
"ERASER 5"; тав 15; " E
TAB 12;" "| T
> г! [17 $ TAB 20; га ДЕ
тав 18;
Figure 10: Changes for Game Variations.
TAB 9; "а": TAB 21;""4 To change: ак ROM Өк ROM
Ага j Number of laser bases:
TAR ON CN d + Change the number in line 110 100
TAB з; "В =m Speed of alien’s laser:
POKE a number from 1-30 into 16428 16515
TAB а; "B аа, Speed of alien's screens:
POKE another number into 168350 16919
LAB T (It is 6 now; try 1 or 2)
E eae Laser base graphic:
РОКЕ new character code into 16621 16716
165516.0 and into 16904 16993
16519 ,223 Alien’s laser graphics
156524,9 POKE new character code into 16527 16622
әре RAND USRA 16525
230 PRHUSE 99
зае SLON щей: Variables.
250 RUN Decimal Initial
d: T
The number or letter indicates the key mog z Boss iia P rus
on which the graphic is found and the 16428 і 3 uii ы
number in () gives the number of times to 16429 2 0 fea ааа tab
press the key. 15430 3 8 gun vosition
100 сал 15531 4 1 gun direction (1,-1)
Тар еще (009 Xa {РУ X. 4 164 32 5 Yr base vosition
120 3: 7; 7; 4 | 16439 6 0 laser position
ISO 0 1v 27-4 16454 7 0 laser vosition
140 T; space; aso 16435 8 0 "Shell" position
190 7:05 то 15435 9 0 "shell" position
160 Ур 3; К; У; В 14437 10 0 "shell" indicator
170 5; Т; 4; 8; (24) А; (24) А 15438 11 6 rotate counter
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52 ` SYNC Magazine
FULLER FD SYSTEM $79.95
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INSTALLATION
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Label
START
DI St
Variations
Variations can be made in both ver-
sions. Figure 10 summarizes some of the
main possibilities. If you have extra RAM,
you can add your own openings and
endings such as suggested in Figure 5.
Note that PEEK 16524=16 can indicate
to a program that the invader was
destroyed.
British TV Differences
Since the speed of British television
receivers is different from that of U.S.
receivers, some adjustment may be
needed. If this adjustment cannot be
made with the vertical hold, then some
changes in the program need to be made
to slow down. For the 8K ROM try POKE
16538,79, and POKE 16556,79; for the 4K
ROM, POKE 16455,80, and POKE
16464,79. These will slow it down quite a
bit, but other values may work better.
(Ed.—SYNC would be interested in
hearing from British readers concerning
their experience with this problem.)
Playing the Game
The goal of the game is to blast through
the bottom protective screens of the alien
ship with your lasers and hit the alien (the
left foot). This will destroy the alien and
his ship. The game begins when you
launch your attack on the alien ship from
your laser base. Since both your laser and
the alien's laser fire only on the perpen-
dicular, you must get your base in position
to hit the ship. To move your base, press
the arrow keys: 5 for left, and 8 for right.
To fire press 0 or 1. Your laser has an
unlimited number of shots. The alien's
laser has computer controlled accuracy
and will destroy all five of your laser
bases if you are not careful. So watch
out!
The game is over when you have
destroyed the alien or when you have lost
all your laser bases. When the game is
over, you can play again by pressing
NEWLINE. If not, press NEWLINE and
BREAK and you will return to Basic.
You can also BREAK at any time during
the game. я
Figure 12: 780 Instructions (4K ROM)
Instruction Comment
LD IX, 16527
OUT (255),A display one frame
LD A,72
LD B,25
LD HL,(15396)
SET 7,H
LD C, 32
CALL 432
LD A, 232
INC в
DZC AL
LD С, 31
CALL ^32
LD A,127
IN A,(254)
set task Гог ЗпгАК key
read keyboard
RRA push break bit into сеггу
SYNC Magazine
index register points to variables
Label
MOVE
CFGUN
L333
MORE
Instruction
RET NC
LD А,231
ІМ A,(254)
2X AF,AF'
LD*AS(IX*?)
AND A
JH М2, РІНЕ
LD 93,95
JR CPGUN
DEC (IX*0)
JR NZ,LEAF
LD A, (LAFI)
ІМС А
LD (IX*-0),A
гр C i159)
LD z,(IX-)
Ll
LD HL,(15396)
ADD HL,3C
ір (HL),0
ӘНАС
LD Dj,E
RL E
ADD HL, DE
LD A,C
ADD A,E
Гр (1543), А
LD (BUY 2
ADD BL,DE
SLA Е
SLA E
ADD AL, JË
DDA РР?
INC A
CF (HL)
LD 3,4
Ja Һ2,СРАУМ
LD А, (1Х+4)
NEG
LD (1х+4),А
To- DA
EX AE, AE?
LDS ҒА
EX АГ, Аг"
LD A, (1Х+3)
BIT 4,C
JR №,1555
ADD A,12
BY БҰТА О,
JR NZ,MORE
SUB 12
ADD A,173
CF (I A+5)
JR NZ,"OVE
Lt LES) „1
LES
LD Ls (1x43)
ШОН
ADD НГ, D.
LD 8C,(16396)
ADD KL, ЗС
LD (16433),HL
10 (#1.),2
Бр: 3/29
JR SHOOT
LD ВЕ/ЗЗ
LD HL, (16433)
ADD HL, VE
INC (1Х+2)
SLT 7, (1Х+2)
JR NZ,ENDF
L5 4:13
ОНИ,
CP, CBL)
LD (HL),2
July/August 1982
Comment
return to BASIC if BHEAY pressed
set mask for tor row
read ke:vboar4
Save in alternate rezister
test laser indicator
continue laser fire
set syne loop
decrement skill counter
move laser zun if zero
restore counter
ВС holds relative gun роѕі+і сеп
Е hodjkds-di*ectYon-(El.-o»-1)
SL points to display fils
допо зат гро Ели
erase gun
push sor ft. bit <0
get D same sign as E
restore зи
HL holds new position
put old rointer into А
update A
replace pointer
put gun in new position
move pointer 5 spaces
load A with "nevline"
compare with new location
sync
reverse direction if necessary
zet olà direction
negate it
revlace it
sync
get keyboard readinz
put into C
save it
get дип position
test "left" key
add 12 if "left" pressed
test "right" key
subtract 1? if "rizht" pressed
add offset
compare with base vosition
begin laser if gun in vosition
set laser indicator
HL holds zun position
move down one line
BC points -to=di svlay
adjust HL
store in memory
fill with laser character
sync
get old laser rosition
move down one line
ircrement indicator
test bit 7 of indicator
erase laser 1f set
check for laser hit base
sync
fill with laser character
MAKE YOUR SINCLAIR
A PORTABLE COMPUTER SYSTEM
MAC (MOHR & Associates Corporation) Now Of-
fers You A Durable, High Impact ABS Plastic Brief-
case That Measures 17?" X 1214" X 412". Wired For
110-60HZ And Ready To Be Used!
You Merely Insert Your Sinclair Components (In-
cluding Printer) In the Preformed Cavities And
BINGO You Have A Portable Computer System.
The Briefcase Has Slots For Tapes, Coax Cable
And The TV Adapter.
$149.95 Includes Shipping & Handling.
Kansas Residents add 3% Sales Tax.
TO ORDER
SEND CHECK OR MONEY ORDER
MOHR & ASSOCIATES CORP.
645 N. Baltimore
Derby, KS 67037
(316) 788-1526/788-3165
MC/VISA ACCEPTED
Bridge Software
Quality Software
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Some UK customer response:
"| have nought numerous other items of software... Yours are
excellent . . . They LOAD мей, have perfect instructions . . .
the most user-friendly | have ever тег. (P.R. Notts)
.. very pleased to find the program load first time and play а
creditable version of Invaders . . Please supply MULTIGRAPHICS. ”
(M.Z. Cumbria)
“Enjoying ‘GAMES’ very much — ‘Letter Square’ is quite
addictive.” (F.W. Manchester)
"Many thanks for the Statistics programme. | am wed pleased
with it.” (A.M. Herts)
1K GRAPHICS (Kaleidoscope. Large Print, Medium Print, Draw s
Picture). Manual only (contains accurate listings, notes,
information and ideas) £4.50/$9
Package of cassette and manuel...................... piede dr £6.00/$12
1K GAMES (Duck Shoot, Moonlander, Hangman, Crossword,
Letter Square). Cassette and instructions ;
16K GALAXY INVADERS in machine code. Cassette and
instructions / /6К RAM pack needed) £4.50/$9
16K MULTIGRAPHICS — create drawings, advertising displays,
etc. on screen. Displays can be saved on tape, printed on your ZX
printer. Cassette and instructions/ /6K RAM pack needed)...£6.00/$12
1K STATISTICS — cassette and instructions 4.50/89
Prices include Air Mail. Send € ог $ check.
BRIDGE SOFTWARE (S)
36 FERNWOOD, MARPLE BRIOGE
STOCKPORT, CHESHIRE SK6 5BE U.K.
and
ZX81
SOFTWAR
SUPPLIES
TIMEX 1000
GAMES, EDUCATION, HOME OR BUSINESS APPLICATIONS
Choose from our Extensive collection of over 100 programs,
far too many to list here so if you don't see something you
like, send for our catalogue, $2.25 handling and --credit on
GAMES your first purchase.
MAZOGS
A large complex maze which contains a glittering and fabulous
treasure. You not only have to find the treasure and bring it out of
the maze, but face the guardians of the maze in the form of fear-
ful MAZOGS. Even if you survive you could starve to death if you
get lost. 3 levels of difficulty. only $29.95 16K
GALAXIONS
Features of an arcade game. Attacks-Defends and keeps per-
sonal scores. only $14.95 16K
BATTLE SHIP
Play against the computer to destroy its battle ships, cruisers,
destroyers, etc. only 10.95 16K
VOLCANIC DUNGEON/HANGMAN
1. Attempt to rescue the elfin princess; mystical monsters, pits,
fireyheavens. Reducing strength and water make the quest
anything but easy.
2. Deluxe version of the classic game, play against second per-
son or computer with 400 word vocabulary. only $10.25 16K
ALIEN INTRUDER/HIEROGLYPHICS
1. You find you are the only survivor on the Explorer Class III
star ship. Try and escape before you fall victim to the alien mon-
strosity that destroyed the crew.
2. Decode the ancient 39 symbol alphabet in time to save a
famous explorer. only $10.25 16K
WUMPUS ADVENTURE/MOVIE MOGUL
1. 1-4 players seek the famous creature in the most famous and
dangerous Wumpus hunt ever.
Features: Super Bats, Pits, Tremors, Swamps, Magic Arrows,
Giant Sea Serpents, Wumpus Muk and Magic Springs.
2. Guide making you through the often hilarious traumas of
production.
$10.25 16K
GREAT UNCLE ARBUTHNOT'S INHERITANCE
You are left $100,000 but first must turn $100,000 of it into a fur-
ther $100,000 by investing in the British Stock Market and Metal
Use your budget wisely to make a fortune. only
You then have à further 26 weeks to
make $100,000 running a soft drink factory. only $70.25 16K
GREAT BRITAIN LTD.
You are the Prime Minister and Chancellor of the Exchequer of
Exchange in 26 weeks.
Great Britian. Your aim is to stay in office as long as possible.
$10.25 16K
AROUND EUROPE IN 80 HOURS
You have a bet of $20,000 to visit 12 capital cities in Europe in
two and a half days, travel agents permitting. only $70.25 16K
HOME-SAVINGS
FINANCE 1
Balance and maintain checkbook. No overdrawn or returned
checks. only $9.95 16K
HOME PLAN 1
Keep your diary in order.
DATES
Keep track of your food and freezer needs. only $9.95 16K
APPLICATION PROGRAMS
TOOL KIT
Provides many special features (line number, search and
only 38.50 16K
replace, free space, etc.) plus special graphics mode and tape
routine. only $10.25 16K
GRAPHICS TOOL KIT
22 exciting Machine Code routines that give you control over
your screen as never before. only $10.25 16K
MICRO-MUSIC
Convert your keyboard into an organ mantle. only $8.50 16K
EDUCATIONAL - Learn
CHESS |
Six levels and analysis options.
CHESS 11
Seven levels and a recommended move option. only $24.95
16K
ZX-BUG
30 in 1 tool. Disassemble. Access all registers, search, modify
memory with cassette routines. only $74.95 16K
BUSINESS - Opportunity
ZX-99 TEXT
Fantastic word processor with output to your printer through our
ZX-99. $29.95 16K
BASIC BUSINESS |
Cash flow control and planning. $76.95 16K
only $12.95 1K
Coming in the next issue:
HIGH RESOLUTION GRAPHICS BOARD AND COLOR
All for your ZX-81/Timex 1000
DEALERS WANTED/INQUIRIES WELCOME
data-assette^, 56 South 3rd. st. Oxford, PA 19363
1-800-523-2909
1-215-932-3626
2Х81 ог TIMEX 1000
data-assette ? Your One Stop Shop
Ай Products Guaranteed
EVERYTHING YOU WILL NEED!! ADD ON TO YOUR ZX 81/TIMEX 1000!! ALL PRODUCTS 100% GUARANTEED !!
NOW GROW YOUR SYSTEM AS YOUR NEEDS CHANGE, AND WE WILL GIVE YOU PRODUCTS, SERVICE, SOFT-
WARE AND ADVICE. WE HAVE BEEN IN THE BUSINESS IN ENGLAND FOR OVER ONE YEAR AND OFFER THIS
EXPERIENCE TO ALL OUR CUSTOMERS.
New Low Prices
1st STEP - MEMORY - RAM 2nd STEP - KEYBOARDS
16K - 32K or 64K FULL SIZE or MINI $75.00
$59.95 - $109.95 or $149.95
En
Each RAM extends the BASIC memory to provide the user space for
all applications.
TAPE Real Professional KEYBOARDS Computer Size and with special
3rd STEP = ZX-99 features like!!!!'Repeat Keys on the full size. Both units are easy to
CONTROL install at home . Supplied with cables & instructions.
Now add Real 'DATA-PROCESSING'' power to your ZX-81 with our
sophisticated extension. Provides 'FULL SOFTWARE CONTROL `` of
four (4) tape decks and a PRINTER interface for any RS 232 Serial
Printer, giving full 132 ASC |! characters of output. Plus!!!!!!
ж ж AUTOMATIC “ТАРЕ TO TAPE COPY"
* х TAPE BLOCK SKIP, DIAGNOSTIC ASSISTANCE
INTRODUCTORY OFFER “9375.00”
Special to New Owners, show us your invoice and order in 30 days
from the date. We will give you this "FULL PACKAGE” for the low
' price of $300.00. 64K RAM + Keyboard + ZX99. Add it to your prin-
ter and for under $400.00 you have full MINI-CAPABILITIES.
ж x DATA RETREIVAL WORD PROCESSING
ж x RS 232 C Serial Printer Interface
EQUALS REAL MINI-COMPUTER CAPABILITIES
BLANK CASSETTES
С-5 5.69 | visa. jw Рн CE d Please rush me: Quantity Price Total H
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plus Shipping
58
STOCK MARKET
PRICE
ANALYSIS
HELP! for the
Small Investor
Now SINCLAIR ZX-81 (16K) owners can do what the professional market traders
do — use a computer to predict price direction. This program tracks up to six stocks,
averages, Or commodities, and produces graphs and uses technical indicators to
help you make trades.
Technical analysis is based on two ideas: first, that the market, like the rest of
human behavior, repeats itself; and second, that there are professionals and in-
siders who know what the market is going to do before everyone else does, and who
place trades in a way that is hardly noticeable. TECHNICAL ANALYSIS attempts to
read the price action and volume figures to determine whether predicable patterns
are developing, and what the professionals are doing.
Professional traders have been using computers to make this kind of analysis for
years, because the manipulation of the data is very complicated and time-
consuming. With this program, you let the computer do the work, and its signals
become a powerful investment tool.
The program makes GRAPHS of the daily prices, of two moving averages, and of
a volume indicator. A booklet that comes with the program helps you learn what to
look for.
The program does an ANALYSIS to signal trend-formation and tum-arounds. It
gives a score for each indicator, and a total score, to help you see whether there is
confirmation among the signals.
USE THIS TO TRADE STOCKS, OPTIONS, AND THE NEW STOCK INDEX
FUTURES!!
This gives POWER TO THE SMALL INVESTOR!
For program tape and booklet send $30.00 to:
NOOTER STOCK PROGRAM
320 East 25th Street
New York, N.Y. 10010
(N.Y. residents, add $2.48 sales tax.)
ZX80/ZX81 Keyboard
Full size 40 key keyboard. All symbols marked in two
colours. Proper typewriter style keys. Old keyboard,
RAM pack and printer still work.
Kit £19.04
Вин £21.65
In/Out Port
24 line—controlled in BASIC. Drive motors, printers
etc. Input or Output.
Kit £11.74
Built £13.87
Motherboard
Drives RAM pack, printer and two other boards.
Kit £14.95
Вик £16.95
Cash with order please. Postage (surface mail) £2.00
per order.
Also many other boards and connectors. Please send
for free illustrated catalogue.
REDDITCH ELECTRONICS
21 Ferney Hill Avenue
Redditch, Worcs.
B97 4RU ENGLAND.
Figure 12: Z80 Instructions (continued)
Label
MISSED
REPLACE
ENDF
SHOOT
BITE
ВЕЗЕТ
ВЕТМ
AGAIN
Instruction
JR NZ,MISSED
EXX
LU (14+5),177
LD 91,7
LD ВС, (16395)
ADD НГ, ВС
DEC -( HL)
LD А, 28
СР (HL)
ВЕТ 2
LD HL,689
ADD HL,BC
LD (HL),13
EXX
LD в,4
DJNZ -2
LD A,14
CF (IX*2)
LD 3,20
JH NZ,REPLACE
LD (IX*2),128
LD HL, (16433)
LD DE,-396
ADD HL,DE
LD B, 31
LD (HL),0
LD (16433),HL
JH SHOOT
LD (HL),0
LD A,(141)
LD B,35
СР (1Х+2)
JR NZ, REPLACE
LD B,35
LD (IX+2),0
DJNZ -2
XOR A
CP (14+10)
JH Z,READ
LD HL, (16435)
LD (HL),0
LD DE,-33
ADD НЫ, ОЕ
ГОА, 2
LD B,28
СЕ (HL)
JR Z,RZSET
LD (16435),HL
INC (IX*10)
LD A,8
10 B,22
Cr (HL)
JR 2,ЗЕТМ
JR C,BITE
LD A,16
LD B,20
СР (14+10)
JR Z,RESET
LD A,13
LD B,19
CF (IX*10)
Ja C,ROTATE
LD (3L),6
ED-B,17
J? НОТАТЕ
LD (HL),0
LD (14+10),0
JR ROTATE
LD (HL),0
Comment
Save the registers
replace laser base at left
HL voints to (D-FIL=)+7
one les: laser base
check for "zero"
return to BASIC if zero
point to bottom left of screen
fill with base character
restore registers
sync
timing loop
check for laser at bottom
sync
indicate laser ending
get old laser pointer
move up 13 lines
sync
erase top of "laser beam"
update pointer
continue erasing laser
check for laser fully erased
sync
sync
timing loop
zero A
compare shell indicator
HL holds shell -cointer
erase shell
move unr one line
check for laser hit shell
sync
update pointer
increment counter
check for shell nit alien
sync
if shell hit alien
1f shell hit shir
check for shell at ton
sync
don't show shell if 3 below top
(so shell isn't carried away
by rotation at bottom of ship)
fill new shell location
take chunk out of ship
reset indicator
loop 80 times
ОЕ=-2
erase а character
SYNC Magazine
Label
READ
SAVE
ROTATE
SLIDE
RIGHT
Instruction
ADD HL,DE
DJNZ AGAIN
НЕТ
EX AF,AF'
3IT 0,А
LD в, 34
JR NZ,SAVE
LD (IA+10) ,1
LD L, (IX+5)
LH a
LD DE,-33
ADD HL, DE
LD ВС, (16396)
ADD НГ, ВС
LD (16435), Н
LD (HL),6
LD 8,24
EX AF,AF'
DJNZ -2
DEC (IA+11)
LD 8,95
JR NZ,SLIDE
LD (IX*11),6
LD AL, (16396)
LD Dz,198
ADD HL, DE
LD A, (HL)
LD D,d
LD EE
INC HL
LD HO. 73
LDIR
LD (D*),A
LD DE, 32
ADD HL,DE
LD A, (HL)
LD D,H
Тр В
DZC HL
Ер 9323
горе
LD (OE),A
LD 3,10
DJNZ -2
LD Е, (14+5)
КЕТЕР»
LD HL, (16396)
ADD dL, DE
LD (HL),0
LD D&,O
EX AF,AF®
ВІТ Ч,А
JR №, ВІСНТ
DEC DE
BIT 2,A
Ja NZ,LEFT
INC DE
ADD HL, DE
XOR A
OR (HL)
LD B,19
JR Z,MERGE
SBC HL,DE
LD 3,17
LD E,0
LD (HL) ,13
DJNZ -2
LD А,(ЇХ+5)
ADD A,E
LD (IX*5),A
JP DISP
July/August 1982
Comment
move left 2 spaces
do again for exploding effect
return to BASIC
get keyboard reading
test "fire" key
sync
set shell indicator
HL holds relative base position
move up one line
BC points to display file
adjust HL
update pointer
fill with shell character
sync
replace keyboard reading
syncronization loop
decrenent rotate counter
sync
restore rotate counter
point to display file
HL points to top left of bottom
of ship
save first character
DE=HL
HL=DE+1
shift 23 spaces
replace first character at right
move to bottom right
save last character
DE=HL
HL-DzÉ-1
shift 23 spaces
reolace last character at left
sync
timing loop
HL holds base position
erase base
zero DE
get keyboard reading
testi. Ser t hi key
DE--1 if "left" pressed
test “right” key
DESO or 1 1f "right" pressed
move right or left
Zero A
test for space and reset carry
sync
move back
sync
Zero addend
replace laser base
timing loop
get old pointer
update,
and replace
jump back to beginning
PREMIUM
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COMPUTER GRADE
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The Micro-Trac™ Generation
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* CASES.................$ .21 $ .20
* Cases recommended to protect sensitive cassettes.
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— Canadian shipping multiply by 2-
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ext. 3005
In Arizona
1-800-352-0458
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MICRO-80 m INC.
2665 Buzby Road
Oak Harbor, WA 98277
— Distributors Wanted —
Ора.
VD board
for Microace,
ZX-80,81
16K RAM
edge connector
Programmable 8255 P.I.A. can
be configured for direct I/O;
polling of peripheral devices,
vectored priority interrupts.
Use it with A/D converters,
serial I/O port chips, relays,
sensor inputs, clock chips, or a
security system.
Play chimes with different tunes
using your computer.
8080 M/L programs, TRS-80
M/L programs will work.
Literature available with
experiments, programs, and
information on how to use the
8255 РТА.
Basic 8255 board $50
add-ons extra
Professional Electronics
109 CHESNEY LN. COLUMBIA S.C. 29209
ZX81 Software: Plotter 1 — A sophisticated routine
that plots and graphs any function.
(16K) $9.99 (U.S.)
Two Handed Euchre—Challenge the computer in this
entertaining and skillful game. (64K) $14.99 (U.S.)
J.C. Software
28 Shipley Rd.
Weston, Ontario, Canada.
M9R-3H8
EDUCATIONAL SOFTWARE (ZX 81, 16K) on cas-
sette. MATHS for 14-17 year olds (3 full pro-
grams). MATHS and ENGLISH for 8-13 year olds:
4 cassettes, 6 programs per cassette, each with
jackpot game plus certificate. $9.50 per cassette
plus $4.00 total for mailing. ROSE CASSETTES,
148 Widney Lane, Solihull, West Midlands B91
3LH. England.
ZX-81/1K
LISTINGS OF 5 GAMES — $2.00
Z—GAMES
P.O. Box 367
Ringoes, N.J.
08551
RAM EXPANSION
ADD ON RAM FOR ZX80; 2K INCREMENTS UP ТО
16K. COMPLETE SCHEMATIC. PARTS LIST.
SOURCES. AND HOW-TO FOR $395 APPR
COST FOR 2K. $20 FOR THE FIRST 2K $13.50
FOR EACH ADDITIONAL 2K. NO ADDITIONAL
POWER SUPPLY NEEDED SEND $395 WITH
SASE TO
DENNIS WEBER. BOX 742
TROUTMAN. М.С 28166
60
4K ROM; 1K RAM
Galaxy
Invaders
Phil Gervais
In Galaxy Invaders you are under
attack by a fleet of enemy spacecraft
which you must destroy before they
destroy you. This game uses the ZX80's
IK RAM, graphics, and screen blackout
characteristics to produce an arcade type
game. The program (see Listing 1) is fairly
simple, but it employs techniques which
are used in the popular arcade games: 1)
insufficient information (you know they
are coming, but you do not know when);
2) the ability to play all day (if you are
good enough); and 3) a running point
total (for self-satisfaction).
A typical game goes like this: First, the
title block appears. You climb aboard
one of the three attack ships in your
squadron, prepare yourself for the worst,
hit NEWLINE, and blast off into space.
Suddenly, you see the enemy ships
approaching! You immediately hit your
firing button (NEWLINE) as quickly as
possible. The enemy craft disappear
quickly, but not before you hit one of
their small reconnaissance ships with a
deadly phaser. Your onboard computer
evaluates your shot. Each ship you hit is
worth either one or two points. Since
your objective is to destroy as many ships
as possible, a high point total is the
measure of a successful mission. Your
new point total is displayed along with
the number of ships you have hit. NEW-
LINE returns you to outer space for the
next round of the battle.
We must note some of the features of
the equipment that shape the battle strat-
egy. Both squadrons are equipped with
advanced radar firing which insures pin-
point accuracy. However, the enemy's
phasers are capable of jamming your
detection gear and vice versa. This insures
your accuracy and disrupts the enemy's
firing.
The scores in this game generally range
from 50 to 100. If you get over 150, you
rank among the best space pilots in the
galaxy. However, if you do not seem able
to win a battle, you will have to have your
engineers redesign the capability of your
attack ships by increasing the value of C
in lines 80-90 by 20 or more.
For those who have more than 1K
RAM the step in Listing 2 gives a bonus
ship at 250 points.
May the luck of the galaxy warriors be
with you! a”
Phil M. Gervais, 714 5th Ave. South, Clinton, IA
52732:
Listing 1: Galaxy Invaders; 4K КОМ, ІК RAM.
2 RANDOMISE
4 CLS
6 LET F=0
8 LET 7-3
10 PRINT ,"GALAXY INVADERS"
12 GO SUB 76
14 CLS
16 FOR 1=1 TO 2OxRND (100)
18 NEXT I
20 РОКЕ 16414,0
22 РОКЕ 16415,0
24 GO SUR 70
26 LET А=РЕЕК (16414)
28 LET В=РЕЕК (16415)
30 LET C=256*x8+A-4
52 CLS
34 IF C«8 THEN GO TO 62
26 IF C<9 THEN GO TO 94
58 IF C413 THEN GO ТО 97
40 PRINT "YOU WERE HIT BY FHAS
ER"
42 LET Z=Z-1
44 IF МОТ 7-і THEN FRINT 7; "#5
HIPS LEFT"
46 IF 7-і THEN РКІМТ 7; "#5НТРЯ
LEFT"
48 IF NOT Z=0 THEN GO TO 101
50 FRINT “POINTS ACCUMULATED: #
EE
52 FRINT "START OVER ІМ NEW GA
LAXY?"
54 INFUT WS
56 IF CODE (ИФ) =62 THEN RUN
S8 CLS
60 БТОР
62 PRINT "DESTROYED ENTIRE FLE
64 FRINT "GOOD WORK."
66 LET F=F+4+RND (5)
68 GO TO 99
70 CLS
2 FRINT , "SHOOT NOW"
74 PRINT ,"лшшшчйшшш"
76 PRINT
78 FRINT
go PRINT,,"SD"
2 FRINT
84 PRINT, "#8"
86 FRINT, "TAAAT"
88 PRINT, "“#G#G",,"SD"
90 FRINT
91 PRINT "SD"
2 INFUT WS
93 RETURN
94 FRINT "DESTROYED SMALL GROU
95 LET Р=Р+2+КМО (2)
96 GO TO 99
97 PRINT "DESTROYED 1 SMALL CR
98 LET F=F+RND (2)
99 PRINT "POINTS: #",F
101 INPUT W$
102 GO TO 14
Listing 2: Bonus Ship; 4K ROM, over 1K RAM.
$ LET Хо
100 IF Р>249 AND X=0 THEN GO S
ЧЕ 104
104 PRINT "жж BONUS SHIP xx"
106 LET Z=Z+1
108 LET X=1
110 RETURN di 7
SYNC Magazine
8K ROM; 1K RAM
Micro Invaders cyril в. smith
18 LET G=@
15 LET G=G+5 реа
28 LET B-15 The invaders come swooping in from
5а БЕТ га, пие space in formations of five space
— t -
28 Сото Ge ships. S mes can са ORAE P
| 52 LET мама —— | times, and they can hide behind eac
In Micro Invaders, a space fantasy 55 ТР маб THEN GOTO 15 other. Hitting one ship results in a forma-
i " 65 LET c=e tion rearrangement and a delay in renew-
S жула ыл ы toa JE BORE тывы. COTS: адв ing the aiek
inclair, the Earth is under attack by a 25 LET HIM) SINT iRNDx1827), ч а: Ace
fleet of Micro Invaders from outer space. 28 н хт M сы ап the ships of the formation are
You are in charge of a mobile inter- ima BOR NER ON n vues destroyed before they reach you, you are
cepter launcher defending the Earth. ies те ASL AND B=AtH) THEN coro assigned a new formation to deal with.
Intelligence has reported that the invad- 119 NEXT МН _ Ө The number of craft destroyed is shown
115 IF INKEY$-' 9 THEN LET C=1 jn the lower right of the display. The
ing ships can be destroyed only by hitting іра IF C-1 THEN GoTo 140 өрк
them just inside the left landing leg. This 1189 IF INKEY$-"S" THEN LET B-P- game is over if your launcher is hit by the
1
. . . . . —_ tt ee i к ae -=S+
requires pinpoint aiming. You control ine IF INKEY$="9" THEN LET: B invaders.
1 ; :
your launcher movement with the arrow 128 80104145, Since the program is quite full, more
keys using 5 for left and 8 for right. You тас PRINT RT ВВ В ecco memory would be needed to add anything
launch your intercepters by pressing the 155 IF Ast THEN LET я-ге unless the efficiency of the program can
158 PAUSE 25 bas d
zero key. 165 CLS e improved.
аа Program notes:
Cyril B. Smith, 4737 Shadowglen Dr., Colorado 252 SOLET Ar 21,280;G-N;" INVACE Line 100: graphics on T and Y.
Springs, CO 80907. Sad: Line 145: graphics on Q and 4. Fa
CHAIN ID EAT iH JE:
: "a 3 erra qu ғы.
yes
ZX-STD BUS INTERFACE
Floppy Disc * ON-BOARD MEMORY
Hi-Res Vid. EXPANSION OPTION
dud # MEMORY - MAPPED PORTS
Мете) ЖРНОУІОЕ5 POWER TO ZX
беса *ALLOWS OVER 6M CABLE
Modem * HI-POWER BUS BUFFERS
A-D * DELIVERY FROM STOCK
D-A
Etc. Etc. Rowers
From over 50 manuf. САЗ ы
ие
OPTIONS:
* CONVERT ZX EDGE CON.
TO RIBBON HEADER $30
*2K RAM EXPANSION $15
*4K RAM EXPANSION $25
AEI со
BOX 18093 AUSTIN |
TX 78760-8093 SIHNIGILNA V IB PEN
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DESCRIPTIONS
P & B SOFTWARE
1155 E. MALIBU DRIVE
TEMPE AZ 85282
If you have a ZX-81 with 1K RAM you can now
have more than ten times the program size (with
filled screen) using this new 2K RAM kit.
Spending $54.90 for a bulky module is no
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62
8K ROM; IK RAM
Comet
Crusher
Chuck Dawson
FLASH!!! Astronomers have spotted a
hitherto unknown comet a million kilo-
meters from the earth. Calculations indi-
cate that it will collide with the Earth's
atmosphere at a shallow angle and will
probably break up into many pieces. Each
of these pieces could destroy a city. Top
scientists have advised placing special
Comet Crusher missiles at strategic loca-
tions around the world with the hope of
blasting the comet fragments into dust
before they can hit any of the populated
areas.
Leaders of countries around the world
have issued an urgent call for volunteers
to man the Comet Crusher missile batter-
ies. Those who apply must have a keen
sense of timing and iron nerves, because
millions of people will be depending on
them. Physical strength is not required,
for one need only push the launch button
to place the missile close to the fragment
as it streaks overhead.
As a successful applicant you have been
assigned to one of the launch sites with
the following instructions:
1) Check your ZX81 computer. If it
has over 1K RAM, enter the program in
Listing 1. Note the following lines:
30 graphics on 3, 8, T, 4
50 graphics on S
110 leave 17 spaces inside the
140 graphics on 3, 8, T, 4, and
asterisk.
66 99
Chuck Dawson,
76118.
6520 Victoria, Fort Worth, TX
2) If your computer has 1K RAM, enter
the program in Listing 2. Note the follow-
ing line:
2 graphics on D.
3) If your computer is a ZX80 with 8K
ROM, add these lines to Listing 1:
85 PAUSE 45
86 POKE 16437,255
4) After entering your program, SAVE
it before you run it.
5) Hit SLOW and ENTER; then hit
RUN and ENTER.
6) After your viewing screen is func-
tioning, you are ready to launch your
pulverizing missiles against the assigned
fragments. To fire press F.
7) Hits are recorded and reported to
the coordinating computer to make sure
that no fragments will slip through the
world-wide network. "ы
Listing 1: Comet Crusher (8K ROM; over 1K
RAM).
REM “COMET CRUSHER“ TO SAVE
вото" същи
1.3-- „АР
25. LET Х=@
a"; TAB 19;"
"PRESS FTO F
ЕЕ 1
" THEN LET A=1
Ub. за
155 IF а-ә THEN GOTO se
130 LET H=H-2
148 PRINT AT н.1е: ron 49:
“: ТАВ 297 4%” став io? “TRAB 19
3 AND нха AND H-O THE
3
ісі THEN SOTO 2
4;
1? THEN GOTO БӨ
ве
INT ат 3.333"
FAUSE zen
СМЕТ CRUSHER™
Listing 2: Comet Crusher (8K ROM; 1K RAM).
SRINT AT 20,19; “wee”
LET xzü
Я=@
IF INKEYS="F° THEN LET Hz1
PLOT х.
LiNPLOT X.Y
LET X= ж+а
LET Y=Y+RND#e-1
IF МОТ A THEN GoTo 14
UNPLOT 40, I-2
PLOT 40. Ізі
IF K=4@ AND Y»I-2 AND У‹т+=
+
n OI АЙЫЛ CTI P3 TUE es менн
QUA GS IR OLG (Л 69 (Л бу 0) O1 TO П) O1 P П)
PR INT
SYNC Magazine
You are the pilot of a space ferry going
back and forth through the asteroid belt.
This calls for highly skilled navigation to
avoid hitting or being hit by the asteroids.
The asteroids are represented in your
navigation tank by the O's, and the posi-
tion of your ferry is indicated by the
asterisk. You control your movement by
the arrow keys 5 and 8.
If your ferry and an asteroid collide,
the asterisk becomes inverse. Then you
must get another ship. You build your
piloting credentials by recording how
many times you have successfully crossed
and recrossed the belt. In 1K the com-
puter cannot keep the count for you.
M. Hampson, 7 Hereford Dr., Clitheroe, Lancs
BB7 1JP, U.K.
Reprinted with permission from The Ultimate
Magazine.
Listing 1.
T REM 1121211131211121111111211111
111111111222222220e22020200D00222
еггегегегеззззззззосзззззззззззз
3333333334444444441444444444444а4
44444444455 555555555555555555555
5555555556БББББЕБЕББЕБВБЕББЕБЕБвЕ.
560566665777 7??? 7??? ? 7??? 2? ??????т-
TPTT?T?T?77
19 FOR #=16544 То 16736
28 INPUT X ғ
за PRINT (STR$ (xX-1800)50) i2 ТЗ
EN ҚТА
4& PORE Z.X
58 NEXT Z
Listing 2.
005,016,12927,014,000,22025,245,002,
862,808 ,215,193,197,814,916,205.
245,0058,062,002,215,12323,015,234,
oei4,016,1297,006,000,205,245,005.
262,000,215,193.,127,9G06,0165,205,
245,003. 062, 003,215, 193,013,121,
254 255, 032, 230. 033, 130,064, 126,
932, 002, 203, 142,254,915, 032,0032.
203,206, 120,254, 001., 232, 002, 203.
134,254, 015,032, 002,203, 198,229.,
e32.,009,012,06^2,016.155,032,001.
613,008 ,00@,121,061,850@,033,06¢.,
а.
2
Listing 3.
з RAND
9 FAST
18 FOR 2-МӘТ PI ТО VAL “27” 3T
EP VAL "3"
20 PORE VAL "160514" +Z, INF (RNC
SE WE SE
2 "16515'"2Z,INT (RNO
URL "O'"4UHL "4"
рг POKE URL “ISSIS” +Z., INT САМО
яі agb t \
30 NEXT 2
40 PORE VAL "1I604117'",NO0O7 РІ
45 SLOW
S@ RAND USR VAL "156344“
NT
та RAND RNO zRND x xRND
July/August 1982
8K ROM; 1K RAM
Crossing the Asteroid Belt
The directions are as follows:
1) Do not use your RAM pack.
2) Enter the program in Listing 1. Be
sure to type in line 1 as listed.
3) Type in RUN and ENTER.
4) Enter all the values in Listing 2. Be
very careful. About halfway through the
list, the ZX81 will run out of memory.
Type CONT (inue) and continue entering
the numbers.
M. Hampson
5) Delete all the lines in Listing 1 except
line 1 by entering the line number follow-
ed by ENTER.
6) Enter the lines in Figure 3. Note: the
graphic in line 60 is an inverse asterisk
(on B).
7) Type in RUN and ENTER and your
journey across the asteroid Бей Берт. ш
It's the best!
2ХСНЕ55 II IS HERE !!! It is the fastest, most versatile Chess program for your
SINCLAIR ZX 81/16K (or ZX 80/16K with 8K ROM).
ZXCHESS II has seven levels of play (up to six levels of "lookahead"!) and its
ability to accept and play all standard Chess moves (including CASTLING and EN
PASSANT) makes ZXCHESS II a challenge for both beginners and advanced players.
Choose your level of play, choose to play Black or White at any stage of the
game - you can even set up the board to examine any special position! For
beginners, ZXCHESS II will even suggest moves for you if you are stuck!
A truly magnificent program that plays a great game of Chess! Available for only
$24.50 (plus $1 post and packing charge) from the following distributors:
Softsync Inc.
Gladstone Electronics
Gladstone Electronics
P.0. Вох 480 1736 Avenue Road 90] Fuhrmann Blvd
Murray Hill Station Toronto MSM 3Ү7 Buffalo
New York N.Y. 10156 Canada N.Y. 14203
63
8K ROM; 1K RAM; 16K RAM
DEF on the Sinclair
Jon Passler
Occasionally a program listing such as
“3-D Plot" from Creative Computing's Basic
Computer Games contains the DEFine
statement which allows the programmer
to define a function in the form
DEF FNA(X)- (expression)
FNA merely stands for FuNction A," and
the variable X in the parentheses following
FNA is termed the "dummy argument."
Usually the expression to the right of the
equals sign in the DEFine statement has
at least one X in it. Of course, variable
names other than A and X could be used.
A simple example would be the state-
ment
DEF FNA(X)=X**2+X
Normally, when FNA is "called" or used
within the program flow, an argument is
given within the parentheses different from
the dummy argument, but which replaces
all occurrences of the dummy argument
in the DEFine statement. FNA(2) would
have the value of 2**2+2, or 6, while
FNA(A+B) would be the result of
(A+B)**2+A+B. ЕМА сап be treated
like any other numeric variable. The only
difference is that it is the result of an
expression DEFined at the start of the
program, outside the program flow, and
the programmer can alter the argument
of the expression.
Jon Passler, 344 Cabot St., Beverly, MA 01915.
64
The definition could have contained
more than one dummy argument or vari-
ables which are not dummy arguments,
such as
FNB(F,G)=F*G-Q/R
Functions can also be used as arguments
for other functions, for example
FNB(3,FNA(A+B))
would be the result of
3*((A+B)**2+A+B)-Q/R
The DEFine statement is useful to simplify
equations or cut down on programming
where one equation is used at several
points within the program.
One way around DEFine in Sinclair
Basic is to replace all FN calls with the
expression in the definition. This often
requires breaking down an equation to
simplify it.
Another is to use the ВК VALue function
which can evaluate a string such as “2” or
“2+2” or even “X**2+X”. The solution
then is to replace DEF FNA with
LET A$= (expression)
and replace the FN call with VAL A$.
The only problem appears when something
like FNA(A- B) appears. We cannot call
the function and define the argument all
in one statement. Generally, if several
different arguments are used in the FN
calls, it is best to set the dummy argument
equal to the argument before calling for
VAL A$, setting, for example, Х= А +В.
Listing 1 is the program for “3-D Plot"
from Basic Computer Games. Here
FNA(Z) is defined in line 100 as
30*EXP(-Z*Z/100)
and in line 150 the argument is
SOR(X*X-r Y*Y)
which replaces all Z's in FNA. Line 150
also sets Z, which is not related to the Z
Listing 1: 3-D Plot, Original Program.
100 DEF FNA(2)230*EXP(-Z* 2/100)
110 FOR X=-30 TO 30 STEP 1.5
120 L=0
130 Yl-5*INT(SOR(900-X*X)/5)
140 FOR Y-Yl TO -Yl STEP -5
150 Z=INT(25+FNA (SOR(X*X+Y*Y) )- . 7*Y)
160 IF Z(-L THEN 190
LIO
180 PRINT TAB(Z);
190 NEXT Y
200 PRINT
210 NEXT X
ТЕЗІ
SYNC Magazine
Get the most from your SINCLAIR
| practical, prog
а
Т : um
aber! Maunder Е EE | S
г v 2 vus D _ : Uti | D No o о Wc
The ZX81 Companion Getting Acquainted With The Gateway Guide to th
by Bob Maunder Your ZX81 ZX81 and ZX80
The ZX81 Companion follows the same by Tim Hartnell by Mark Charlton
format as the very popular ZX80 This informative volume for the new The Gateway Guide is a practical pro-
Companion, and assists the ZX81 user ZX81 user contains more than 70 pro- gramming manual for the beginner that
in four applications areas: graphics, grams to help the reader get the most furnishes over 70 fully documented pro-
information retrieval, education and from his Sinclair computer. Game grams. The majority of the programs
games. This practical guide contains programs include Checkers, Alien have been written for easy conversion
scores of fully documented short rou- Imploders, Blastermind, Moon Lander, from machine to machine (ZX81, 4K
tines plus complete programs and a dis- ^ Breakout, Star Burst and Derby Day. The 2Х80 or 1K ZX80). The Gateway Guide
assembled listing of the ZX81 ROM book also shows programs for cascad- describes each function and statement,
Monitor. "Thoughtfully written, detailed, ing sine waves, plotting graphs and illustrates it with a demonstration rou-
and illustrated with meaningful pro- tables, data sorting, equation solving, tine or program, and combines it with
grams. —MUSE plus the use of PLOT, SCROLL, PRINT, previously discussed material to help
512" x8",132 pages. #17Р $8.95 ($2.00) TAB, PEEK, POKE and much more! you understand your computer.
51/2" x8", 120 pages. #15У $8.95 ($2.00) 5⁄2" x 8", 172 pages. #160 $8.95 ($2.00)
Computers for Kids (Sinclair Edition) by Sally Larsen
This new edition of Computers for Kids is written specifically to introduce
children aged 8 to 13 to the ZX81. The book requires no previous knowl-
edge of algebra, variables or computers, and it enables a youngster to .
program a 7Х81 in less than an hour. There's also a section for parents
and teachers. "Computers for Kids is the best material available for
introducing students to their new computer."
- —Donald T. Piele, Professor of Mathematics,
еи University of Wisconsin-Parkside.
« 812" x 11", 56 pages. #125 $3.95 ($1.00)
All volumes are softbound.
(TT RET eee
Creative Computing Press, Dept. 7720, 39 East Hanover Ave., Morris Plains, NJ 07950
VS
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——— M— —=— >= =
in FNA(Z), to an integer value using the
FNA call. This program is translated into
Sinclair Basic (8K ROM, 1K RAM) in
Listing 2. Here the string variable A$ is
used to replace DEFine and set the
argument equal to
SOR(X*X T Y*Y)
in line 145 before calling for VAL A$. A$
is an input since several different functions
are plotted. The same results could be
obtained by adding
146 LET A—30*EXP(-Z*Z/100)
and changing VAL A$ to A in line 150,
except that line 146 would have to be
edited each time the function is changed.
The functions are slightly altered to
run on either 1K or 16K RAM. Neither
program, however, will work correctly
with defective 8K ROMs. The plots appear
within a circular X-Y plane tilted about
30 degrees toward the viewer with the
curve rising above or falling below the
plane.
Try the following functions with the
1K program:
20*EXP(-Z*Z/100)
20*SIN(Z/10)-15
SOR ABS(150-Z*Z)*.4-2
20*(COS(Z/16))-5
20-20*SIN(Z/18)
In the 16K version all the five functions
above are held in F$ (see Listing 3). Each
function word such as SIN uses only one
byte in F$. At line 180 a zero is POKEd
into DF-SZ, which is the system variable
with the number of lines (usually two) in
the lower part of the screen. Entering a
zero into it allows printing the function
on the 24th line. An input cursor will
crash the system if called for when there
is no room for it; so lines 330-340 replace
a dummy input to stop the program
temporarily (press any key to continue).
This is a rather unusual example of an
occasion when using a string variable to
hold a function or functions can be useful.
The technique would also be useful where
a function is used several times within a
program to facilitate the translation of a
DEFine statement or to highlight a function
at the start of a program.
To use the programs, enter Listing 2,
press RUN and NEWLINE and then enter
one of the five functions above and observe
_ the results. If you have 16K, enter the
expanded version in Listing 3, press RUN
and NEWLINE. However, since the func-
tions are already included in the program,
you do not have to enter them again. Mg
66
зве IF Z«-L THEN GOTO 190
17o LEF ЛЕЕ
1за PLOT X+20,Z-5
199 NEXT 7
210 NEXT X
Listing 3: 3-D Plot for Sinclair (8K ROM, 16K
RAM)
зае REM 3-D PLOT
118 DIM F$í(&5.16)
122 LET F$(1)-z"25xEXP (-Zx2.100
зза LET F$i2)2"25x5IN (2710) -15
Y
— DOT) fe 3 OO D) P eh ene pa те
пра RS I UO CD sd n
GAGS AROG AGD |
Listing 2: 3-D Plot for Sinclair (8K ROM, 1K
RAM)
ІМРОР HS
QR х--га TO ге
LET L-e
LET Y1-z5xINT (SOR (408-X#X}
FOR Yzy3 TO ТЕР -5
LET Z-SQR (XsXx4vY FY)?
LET Z-INT (2S54UHL RH$-.7sY)!
NI
338 PAUSE 9999 1 В
340 IF INKEY¢="" THEN GOTO 338
350 CLS
SYNC Magazine
(а
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Two Excellent LAS VEGAS Style Program. Listings
For Only $1 (ZX81-— 16K)
Lucky 7 Slot Machine
* Styled after an actual "bell"
3 reel slot machine with correct
payoffs and token distribution
Fully animated - money goes
into slot, handle is pulled,
reels spin and stop in sequence,
payoff coins fall into the pay-
off trough
Lots of fun - а very addictive
game
» Vegas 21 Blackjack
* Most complete blackjack game
available - split pairs, double
down, асе%5 value automatically
adjusted, dealer stands on 17,
draws to 16
* Uses 5 decks, reshuffles when
appropriate, will advise tens
ratio and distribution of cards
left
* À good way to learn the game or
to practice before going to a
real casino
Don't miss this opportunity to get these two excellent programs at
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satisfied.
ZX81 OWNERS with 16K RAM!
IT'S READY---ARE YOU?
VT FIG $14.95
200,
If sọ, you get:
*24-row/full-screen displays
*Nearly 2K of machine code
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*A 4K Star Atlas as the moving
backdrop during enemy engagements
*9-each fuel and skill levels that
are interlocked for more "reality"
*4 ways to lose---no fuel, no oxygen,
no gun power, or no shields. 1 way
to win----destroy ALL enemy craft.
*An enemy data generator imbedded in
the run as part of the "action"
*"Blink"-less pauses in BASIC
*Stick-on/peel-off custom keys
*In-depth booklet explaining both
the "game" and the program
*Shipped on a certified cassette
1 copy each side
Greenville, SC 29608
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16K Programs for either ZX80-8K or ZX81
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*POLSAT & GEOSAT-space age Ham Radio uses
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4K ROM (8K ROM); 1K RAM
Handling Strings from
Another DIMension
Ken Berggren
Does this story sound familiar? One day,
Fred found an excellent short program in
a magazine article and he decided to
translate it for his ZX80. But after entering
only a few lines of the program, he ran
into a statement like this:
250 DIM NS(4)
"What in the world does that mean?" he
asked himself. When he could not answer
that, he consulted a friend with a TRS-80.
His friend explained that it works just like
a regular DIM statement but with strings
instead of numeric variables. That is, DIM
N$(4) sets up four strings with the same
name, N$, but individually numbered 1-4.
Fred frantically flipped through the pages
of the ZX80 manual and found the terse
explanation of the DIM statement on page
89. But there was nothing there about strings.
So, he set aside the magazine article and
decided to stick with programs written
just for the ZX80.
Well, if Fred sounds like some people
you know, then consider this article dedi-
cated to them. SYNC is a fine magazine,
but it cannot publish every program that
will work in the ZX80. And just because
you cannot use a statement like DIM N$(4)
does not mean that you cannot translate a
program that uses it.
Now you 8K ROMers realize that your
supercharged machines will DIMension
strings without any hocus-POKEus, and
you may be tempted to turn the page on
me. But stick with me because I think that
you will find this technique very interesting
if not useful. Anyway, from now on we will
be talking strictly in terms of the 4K ROM.
It is true that the people who designed
the 4K ROM left out the ability to DIMen-
sion strings. However, with a few well-
placed POKEs, you can plug up that hole
in the 4К ROM.
Ken Berggren, 104 Ridgeway Ave., Louisville, K Y
40207.
68
For example, enter this short program.
100 FOR I=1 ТО 4
110 POKE 16450,1+37
120 INPUT AS
130 NEXT I
The A in line 120 is stored in the memory
location 16450. The code for an A is 38,
So, at present, a 38is stored at the location
16450. When you RUN this program, it
will execute lines 110 and 120 four times.
The first time through, line 110 will POKE
a 38 (14-37) into the location 16450. Then,
line 120 wil] INPUT А5. But the second
time through, line 110 will POKE a 39
(2-37) into location 16450. Since 39 is the
code for a B, line 120 will then INPUT BS.
This program actually changed itself! The
third time through the loop, line 110 POKEs
a 40 (3-37) into the memory location, and
line 120 will INPUT C$. When the program
is finished, it will have stored four strings:
A$, B$, C$, and D$. You can imagine that
these are numbered 1-4 because when 1- 1
you INPUT А$ апа when I—4 you INPUT
D$.
RUN the program and enter four words.
Now change line 120 to 120 PRINT А5
and then GO TO 100. The method will
work with INPUT, PRINT or any other
string functions.
Some of you may thinking, "Big deal.
What good is all this?" I think that the
following two programs will illustrate the
virtues of this technique.
The first program is a simple sort program.
We all know that computers are very good
at putting numbers in order. And since
computers store letters as numbers, they
are also good at putting words in order
(alphabetical order, that is). The program
will alphabetize up to 25 words and will
display up to 22 of them.
Using the program is simple. Just enter
the number of words you want to alpha-
betize and then enter the word with a
NEWLINE after each one. When you have
had the last word, the program takes over,
and, a few seconds later, the words are
displayed in alphabetical order.
I think that it is worth noting line 240. I
do not know if other Basics let you use
inequalities with strings, but ZX80 Basic
does. That is a very nice feature. If you
want to put the words in reverse order,
simply reverse the inequality.
This program is not so great by itself.
But it could be developed into a good
utility program for handling a list of the
names of friends for an address book or
names of students for a grade book. It
could possibly be adapted to help teach
dictionary skills.
The second program illustrates the
technique by computerizing a card game
played something like Rack-O (by Milton
Bradley). The POKEing is used to call
each player by his name rather than the
impersonal PLAYER 1, PLAYER 2, etc.
In this game, the players are dealt ten
numbered cards. The remaining cards are
placed face down, and the top card is
turned face up to form a discard pile as in
Gin. The object is to get ten cards in
numerical order (not necessarily consecu-
tive order). This is done by drawing a card
from either pile and exchanging it for one
of your cards.
In this version, of course, the computer
handles all the cards. First, it shuffles them
and places them into each player's "rack."
Then the first player's cards are displayed
and he is asked if he wants the card showing
in the discard pile. If he does not, he enters
“NO,” and he is given a card from the face
down pile. If he does not want that card,
he enters "NO" again and his turn is over.
If he decides to take either card, he enters
“YES” and the computer will ask where in
his “rack” he wants the card to go. The
player then enters a number 0-9. His card
will be placed in that position, and his turn
will end.
At the end of each player's turn, the
computer will display the cards that the
player has in order so far. Then a NEWLINE
will start the next player's turn.
The game ends when one player get his
cards in order. To start a new game you
have to RUN the program again.
If you have more than 1K of RAM, you
could probably teach the computer how
to play the game and then play against it.
You could also allow more than four players.
But be careful. Any modifications of these
programs may affect the POKE locations.
To make sure, LET I=0 and then GO TO
the POKE statement in question. If the
next statement does not contain a 9$ after
you do that, you will have to change the
POKE location until it does. But trial and |
error will not work very well if you make
big changes or if you write your own
programs. Then you will need a more exact
method of finding the location of a specific
byte in a program.
SYNC Magazine
1K Z X я ADULT GAMES
TAS S DOR SPECIALITY
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SHIFTING REQUIRED). MEASURES 8?" x 4".
INFL MAJ DOLE TERM
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FOR MORE INFORMATION SEND SASE OR TO
ORDER SEND CHECK OR MONEY ORDER TO:
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send to: AUTOMATA LTD.,, 65A Osborne Road, Portsmouth POS ЗІК, ENGLAND
STRUCTURAL
DESIGN
ForZX-81 8К/16К
Programs include GRAPHICS
STEEL BEAM DESIGN $29
COMPUTER =
NEWSLETTER <?
A NEWSLETTER FOR POCKET COMPUTER USERS
This timely, compact publication provides up to the minute
information on pocket computers, including models such as
the Radio Shack TRS-80 PC-1 and PC-2, Sharp Electronic's
PC-1500 and PC-1211, Casio, Panasonic/Quasar HHCs, and
others as they are announced. We only cover PCs capable of
executing a high level language such as BASIC.
О Up to the Minute News O Product & Equipment Reviews
О Important Operating Tips O Practical Programs O More
By Subscription Only: for a calendar year period (January —
December). You get all issues published to date for the calen-
dar year in which you subscribe, at the time you subscribe.
12 Options of Beam Type and Loading MC/VISA Phone Subscriptions: (203) 888-1946
О 1981/82 Charter Subscriber (Issues 1 — 20). $40.00 іп U.S.
(U.S. $48.00 to Canada. U.S. $60.00 elsewhere.)
О 1982 Regular Subscriber (Issues 11 — 20). $30.00 in U.S.
(U.S. $36.00 to Canada. U.S. $45.00 elsewhere.)
O Sample issue. $3.00 in U.S. (U.S. $4.00 elsewhere.) *Due то
credit card minimum, this item cannot be charged.
TIMBER BEAM DESIGN $29
3 Options of Beam Type and Loading
Orders must be accompanied by payment in full. We do not
issue invoices for the POCKET COMPUTER NEWSLETTER.
Thank you for your remittance.
Choice of Timber Grade and allowable Stress
Шаға o LUPA EI DUNS Qa C CL roS D m audi T EX n RN
КӨШЕГЕ dou LE ue UM X qr с rec у с ЕС NM
DORAN ENGINEERING, P.A. Sr M T
113 South Chestnut Street We VERA RET жн ДЫ DRE UEM ee
PLEASANTVILLE, NJ 08232 i PUT мох MEO ur pacer
КРТ D uou Do ARIS СИ MN cn LOTES RS Le OM M а
(609) 646-3111
MASTERCARD
POCKET COMPUTER NEWSLETTER
35 Old State Road, Oxford, CT 06483
One way is to count the bytes in each
line and add them up. Every line has two
bytes for the line number (no matter how
many digits), one byte for the Newline at
the end of the line, and one byte for every
keystoke in between. So, in the example
program, line 100 takes 9 bytes, line 110
takes 14 bytes, and line 120 takes 3 bytes
up to the A for a total of 26 bytes. Add 26
to 16424, which is the starting address of
every 4K ROM program, and you get 16450.
That is the actual location of the A in
memory. However, counting all the bytes
in along program is a very tedious chore. I
found a better way.
When USR(24) is put into a program, it
stops the execution of the program and
returns the starting address of the next
line. Toillustrate, insert 115 PRINT USR(24)
into the short program and then GO TO
115. 16458 appears on the screen because
that is now the starting location of line
120. Line 115 takes 11 bytes so, when it is
deleted, line 120 will move up 11 bytes to
16447. Adding the three bytes of line 120
again shows that the location of the A is
16450. USR(24) is an invaluable utility
whenever you need to know the location
of a byte in your program.
A lot of programs out there in books
and magazines can be adapted to the ZX80.
But sometimes vou really have to work to
get them to. Now the lack of DIMensioned
strings is no longer a problem. There are
other shortcomings in the 4K ROM in
dealing with other Basics. Yet, with a little
determination and ingenuity, you can
usually get around them.
Program 1. Alphabetize (4K ROM; ІК RAM )..
100 FRINT "HOW MANY ENTRIES?"
110 INFUT N
120 FORI-1 TO М
130 PORE 16478, 1+37
140 INFUT A$
КОО NEXT I
200 FOR I-1 TO N
210 FOR J-1 TO N-I
220 (PORE 1555712?
250 PORE 16340, J+38
240 IF BS:C$ THEN GO SUB 900
239 МЧЕХТ J
260 NEXT I
200 FOR 151 TO М
SIO PEE. 16054, Та
220 PRINT D$
550 NEXT I
540 STOP
200 POKE- 166598, *57
910 FORE 16664, JES
920 PORE 16667, 5+38
950 FOKE 16673,49+58
940 LET Z$-Ef
950 LET F$-6G$
960 LET НФ=2%
970 RETURN
Notes:
100-150: Get the words.
130: Changes AS.
200-260: Sort the words.
220: Changes B$.
230: Changes C$.
300-340: Display the words.
310: Changes D$.
900: Changes ES. |
910: Changes Е$.
920: Changes G$.
930: Changes H$.
900-970: Move the words.
Sample Run
FLAYERS(2-4)7 2
PLAYER 1 LORI
FLAYER 2 KEN
2...
SHOW CARD=37 TAKE? N
DRAWN CARD=20 TAKE? =
FLACE? 4 |
Pics
Ne
YON O Gri
SHOW CORD-32 TARE?
FLACE? e
_Program 2: Card Strings (4K ROM; ІК RAM)...
100 FRINT "PLAYERS (2-4) ?"
110 INFUT N
120 FOR Ісі ТОМ
120 FRINT "FLAYERS":I
140 FOKE 16489,1437
150 INPUT A$
160 NEXT I
190 LET E-20-10XN
200 DIM ЕЕ)
210 FOR 1-1 I0 E
220 LET FP=RNDCE)
230. IF CCP) 20 THEN GO TO 220
240 LET СР) =]
230 (NEXT 1
ЖО LET ЕЗЕ-19
400 FOR Ісі TO N
410 CLS
415 LET Тео
420 FORE 16616, ЕЛУ
430 PRINT BS
425 PRINT
440 FOR J-o TO 9
450 FRINT J;
452 FOR L=0 TO C«JXN-*-1)/N/4
454 PRINT "€";
456 NEXT L
450 FRINT CJ XN IO
460 IF To THEN GO TO 490
465 IF Т>9 THEN GO TO 800
470 IF CCI¥N+I) C(I XN4+N4+T)
RE TURN
480 LET T=T+1
490 NEXT J
495 PRINT
JOO LET ¥$="SHOW"
310 PRINT Уф; "#САКО="; ССР); "ЯТА
REY
520 INFUT 24
530 IF 2%>"Х" THEN GO TO 609
340 IF Y#="DRAWN" THEN GO TO 65
m.
5950 LET FsP-1
360 IF РЕ THEN LET F=E-19
570 LET Y$=" DRAWN"
эво GO то 510
600 FRINT "PLACE?"
610 INFUT J
620 LET Т-С(УЖМ+Т)
630 LET СОЖМ+Т) =C CF)
640 LET C(P)=T
650 CLS
660 LET T=1
670 50 SUB 420
680 ІМРОТ 7%
700 NEXT I
710 GO TO 400
BOO FORE 16966, [+27
810 FRINT Съ; "#WINS"
THEN
Notes:
100-160: Get the players.
190: E=total number of cards.
200-250: Shuffle the cards.
300: P=pointer to show card.
410-490: Display a player’s cards.
452-458: Spaces each card over by magni-
tude.
465-480: Part of winner test subroutine.
500-580: Players pick their cards.
600-640: Chosen card put in “rack.”
650-680: Test for winner.
Display cards in order so far.
700: Next player’s turn.
710: Back to player 1.
800-810: Print the winner.
SYNC Magazine
8K ROM Versions
Although the article is intended to help
4K ROM users, we thought the SK ROM
users might like to use the programs so
the 8K ROM Versions are also given below
in Programs 3 and 4. я
_Program 3: Alphabetize (8K ROM; ІК RAM). |
PRINT “HOW MANY ENTRIES?”
INPUT ы
De
кым»
PVH PG
HONBA
г
м
и
p
им
<.
A
4—1
(2-і) THEN f
D CO HEN
зза мЕХТ I
340 STOP
94a LET 2%=Я $ 1:1
950 LET НЕ! =А $ 1+1}
960 LET Я& {1+1}: -Z$
970 RETURN
Program 4:
— — Card Strings (8K ROM; over IK RAM). —
PRINT “PLAYERS (2-41 7"
INPUT N
219 FOR I-1 то E
220 LET P-INT (ВНОЖЕЗ +1
IF СҰР) >а THEN GOTO 22a
240 ааа ЕТ
Ji
152 FOR 1 -а то С СН + ТЗ „ма
454 PRINT " s
456 NEXT Е
458 PRINT CiJxN-I)
460 IF Т=@ THEN GOTO 4.38
IF T»9 THEN GOTO вее
470 IF СіЈЕМ+І) >С CUSN4+N4T)
RETURN
ізе LET Т=Т+1
ыза NEXT J
495 PRINT
сага LET vY$-2"&
в PRINT Ys"
INPUT e
IF 24» "Х" THEN СОТО баа
IF 2 "Бевиме THEN GOTO 558
S50 LET P=Pt+i
IF POE SAREN LET Р=Е- 19
"DRRUN
THEH
HOW"
CARD = сое». “та
га NEXT I
та GOTO айас Ир ge
e PRINT Въ: т: HINS
July/August 1982
CYBORCWARS
©
NOT ANOTHER TOY
BUT A COMPLEX SIMULATION OF FOUR MILITARY- INDUSTRIAL
ECONOMIES LOCKED IN A DEADLY STRUGGLE FOR SURVIVAL.
ONE TO FOUR PLAYERS COMPETE WITH EACH OTHER AND/OR
THE COMPUTER.
BALANCE OF POWER DEPENDS UPON
SKILL IN DEVELOPING RESOURCES, USE OF ESPIONAGE,
EXPLOITATION OF ALLIANCES, AND UTILIZATION OF MILITARY
POTENTIAL.
REQUIRES ZX81 WITH 8K ROM AND 16K RAM.
ста
F
ORDR FORM FOR СВОЮМВЮЎ
Send $14 (plus $1 for shipping) to:
STRATAGEM CYBERNETICS, INC.,
286 Corbin Place, 2E, Brooklyn, New York 11235. V
MM НА LM
MR NES OUO | um
IQ e af 4
ex URS та
5 Se
PROGRAMMING KITS
(Learn by doing)
from Systems and Solutions, Ltd.
Programming is building, and like building with blocks, bricks, or milk cartons, a
builder needs the materials to build with. We provide, in kit form, the building blocks
with instructions that lead the kit-builder through the construction of a program from
scratch. The program can be run atthe end of each step and will take shape as the kit
steps are completed. These kits are made for a minimum system of the ZX80 with 1k
of memory and include translation for ZX81s as well as guidance for going further.
Our aim is to provide the personal joy of programming as well as the fun of playing
with the final result.
PRISONER - Cooperate or trick your
partner (the computer) to get enough
money to buy your way out of jail. Com-
puter strategies are described as part of
the kit. Some are effectively unbeatable in
only 1k of memory.
$4.95
MAZE 1.0 - You are at the entrance of
your own 16 room maze with a treasure in
one room. Given your room number and
the treasures room, can you find the
treasure?
$3.95
ZX-TREK 1.0 - You аге the Captian in
sector after sector of space that must be
cleared of Klingons. Your shields' energy
is reduced based on the strength of the
enemy's hit, you can fire photon tor-
pedoes, and warp to another sector dur-
ing your 5 year mission.
$4.95
TO ORDER: Send your name, address,
and check to: Systems and Solutions,
Ltd., 5054 Kenerson Drive, Fairfax, Vir-
ginia 22032. (Additional overseas post-
age: $.50/kit.) Please allow 4 weeks for
delivery. Free catalog available.
71
SINCLAIR ZX81 & TS1000 SOFTWARE
Fifty games for less than $2. ea.
Send SASE for FREE catalog to:
BIOCAL SOFTWARE
340 Cypress Dr.
Fairfax, Calif. 94930
4 8K, IK BASIC Programs - Sketchpad,
Combinations of 7, Enterprise (picture
only) and Hebrew Tutor, $10.00.
Reply To
DRRP, P.O. Box 3664
Peabody, Mass. 01960.
* ZX81 KEYBOARD TACTILE FEEDBACK *
FEEL WHERE YOUR KEYS ARE!
TOUCH TYPING POSSIBLE, HELPS STOP
MISSED KEYS, SIMPLE TO INSTALL OVERLAY.
$3.95
P. HARGRAVE
SITE V, RR4,
NANAINO, BRITISH COLUMBIA
V9R 5X9 CANADA
72
GRAPHICS, HIGH-SKILL
PLAYING ALGORITHM
PROGRAM LISTING — $2.00
INTELLECTUAL GAMES
193 PEACEABLE ST.
RIDGEFIELD, CT 06877
$39.95 (KIT)
$59.95 (A&T)
ANALOG INTERFACE FOR THE ZX81
Welcome your computer to the “reai world" of analog
signal processing VOTEM is a complete package, con-
sisting of the necessary hardware and software to enable
your computer to measure voltages and temperatures.
VOTEM also includes circuitry that conditions the tape
signal for dependable LOADs.
* Software compatible with Timex TMS-1000, Sinclair
ZX81/80-(8K)
* Requires absolutely no modifications to computer
* Measures voltages and temperatures
* Probe provided for air and liquid temperature
measurements
* Resolution is better than 14 bits „00. 00005V ог 0.04
degrees C)
* Voltage range oí + 1V can be expanded with on-board
resistors
е Low power, requires less than 20mA at +11V
unregulated
• Сап be powered from computer's supply (cable included)
* Tape signal conditioning circuitry
* Tape signal monitoring capability (audio and visual)
* Manual includes detailed kit assembly and calibration
е Software for calibration and applications fits in 1K RAM
* Instructions for adapting to other Z80 computer systems
* Conipact, 1" by 4" by 3"
Also, static RAM chips, 6116P-3 (2K by 8) with instructions
for upgrading Sinclair ZX81 computer from 1K to 2K. Only
$11.95 each. Send check or money order. Include $3 shipp-
ing and handling.
Down East Computers
P.O. Box 3096
Greenville, NC 27834
OTHELLO FOR 1K
The 8K ROM and 16K RAM have
given ZX80/81 users new possibilities in
programming their own games. Alien
Treasure is an example of how some of
these new capabilities may be used.
In Alien Treasure two kinds of treasure
are scattered over the surface of a planet
far from earth. Your ship has landed, and
you have sent out your robot searcher
which you guide from your control room.
The field of search shows on your ZX81
as a full screen display. The treasure is
marked by inverse video periods which
are worth one point each and by inverse
video asterisks which are worth 10 points
each. (You can set the values in your own
currency if you wish.) However, there are
always hazards in searching for treasure.
In this case a powerful monster is guard-
ing the search area. While your robot is
attempting to pick up the treasures, you
must guide it to avoid this monster which
appears on your screen as an inverse
video 0. Your robot, shown as a graphic
square, is moved about by the use of the
cursor control keys 5, 6, 7, and 8. The
robot also can take a jump away to a
random position in the same column by
using the 0 key. However, you must use
this 0 key with caution because the robot
may land right on top of the monster.
The current total of your successful
treasure gathering is displayed on the
screen in the upper left corner. The total
you must beat is displayed to the right of
yours.
The game uses a 22 * 32 array to keep
track of the treasure locations. When the
game is run, it takes about 20 seconds for
the screen and the array to be set up and
loaded with the proper values. So do not
hit the BREAK key too soon because you
think the program is in an infinite loop.
Before you SAVE this program, exe-
cute the CLEAR command. Otherwise
you will save the entire array along with
the program, and it will take much longer
to SAVE and LOAD in the future.
Alien Treasure has proved to be an
interesting and challenging game for those
Gary G. Chandler, ATU Box 283, Russellville,
AR 72801.
Bruce Birmelin/Paramount Pictures.
who have tried it so get out your keyboard
and start the search.
Line notes:
30: inverse space
36: inverse asterisk
44: inverse period
65: inverse zero ;
66: inverse graphics on A
73: inverse letters in “”
85: inverse space
89: inverse space "s.
1 LET С1=@
2 REM TREASURE CHASE
4 REM BY GARY G. CHANDLER
5 LET х-е
Б LET Y=16
7 LET Ył=Y
& LET хіӛішх
9 LET A=INT (БМО #22)
18 LET B=INT (БМО #52)
12 LET С=@
20 DIM Ht22,32)
26 FOR Т=@ TO 21
25 FOR J=@ TO 31
за PRINT AT I.J: B"
31 IF I= OR J=8 THEN GOTO 58
32 IF NOT RND<.@5 THEN GOTO ас
за LET HII-c«1,J0€1)-z
36 PRINT. AT Т. 4; HM"
46 IF NOT RND«.1 THEN GOTO 50
42 LET HII-«1,0431)-1
44 PRINT AT I.J;: "№"
57 IF Н‹А+1, В+1) =2 THEN LET c=
IF Hiín-i,P-1)-2 THEN LET Ht
В+1,В+1; =@
54 IF на + 1,В+1) =1 THEN LET =
C+i 7
20 IF HiAti. 8+1} =1 THEN LZT Hi
H+14,B6+1)
$2 IF Съса E ws
aT
m
+ OD
ET Y=
58 IF х-а AND Y=B THEN GOTO са
59 IF NOT INKEY$="" THEN PRINT
AT AB; HN"
95 IF INKEY$="@" THEN LET A=IN
X сите
INKEY$="5" THEN LET BsE-
1
1776 IF INKEY$-"5" THEN LET Б=Б +
уана ТЕ INKEY$="6" THEN LET Я=&+
қ 129 IF INKEY$-"7" THEN LET fn-n-
132 IF я›21 THEN LET псих
ET
140 IF X=A AND YzB THEN GOTO га
1680 GOTO 55
288 PRINT ЯТ 19,10; "++ СОТ ХОП
202 PRINT ат ех“
205 PRINT ат Зө, 5;" PLAY AGAIN
rts INPUT
Gg
88 IF DE THEN STOP
510 GOTO.
SYNC Magazine
YORK 10
BASF-DPS
WORLD STANDARD TAPE
MONEY BACK
А GUARANTEE
£^. COMPUTER GRADE
teens m^. BLANK CASSETTES
LIGHT PEN
for ZX81 UNDER $70
DRAWS ON ANY TV SCREEN
: Erase & clear by iust
2 ай ons * touching the screen!
“We monitored th |
with a specially bui
lutely no dropouts No
"5,
g
Beaverton, OR
Calif. residents add 6 sales tax
Shipping 1 дог $2. 2 дог $3 50
Moe $4 50 Each additional doz
white or cll tec QUANTITY овсоцита
очну € 6X INTER
= = | К INTERNAL MEMORY
er оты
SUPER GRAPHICS MODULE Add 4K or 6K as you
Lets you control every need it!
VORH IO Computeruore dot on your screen!
24573 Kittridge St., А-1 Canoga Park, CA 91307
CONTROL BOARD (8 1/0)
Home Proiects, Robotics
No special commands-- Easy to use
ure MAIN
Nic UD E ee
$69.95 KIT:$49.95 РСВ $15. чыш?
EASTHILL,OAKHAM,MA O1O68
eEAGLE LANDER-1K ALL
Moon landing simulation LISTINGS
ePICTURE PLOT-IK $2.00
M/C Graphic routine
ФМЕАСА-МОВРН-16К
Survival in cafeterias
eTEXTER-16K
Text editor, printer commands
Send 20€ for full list
ALL listings explain programs
in detail.
EXPANSION BOARD
Buffered Bus/Development Board for
marketed and user built peripherals.
Offers significant yet inexpensive access to ZX81 hardware.
Make check to:
BOB LUCAS
401 М. GEYER ROAD
KIRKWOOD. MO. 63122
All lines from
Gold plated €
fingers.
computer port
are on bus & in
same order.
Buffered Data,
Control & Address
lines. Data bus
is two-way.
Optionai
volt reg.
Circuitry
gives access
to addresses
8K to 16K for
memory or
memory mapped 1/0.
Two types of
connectors:
apo Әбен
ZX81 ASSEMBLER
9 chips needed;
all parts are
standard.
Fastens to ZX81.
2 PASS STANDARD Z-80, SYMBOLIC
EXPRESSIONS, DECIMAL /
HEXADECIMAL, 12K BASIC AND
MACHINE CODE.
ZX81 DISASSEMBLER
Improved Model:
Bare Board $40*
With connector to port
and complete documentation.
Finest quality board.
Plated thru holes.
solder mask. legend.
PROMPT DELIVERY.
HUNDREDS OF SATISFIED
USERS:
Please send stamp
for more info.
STANDARD Z-80, 22 CODES IN5
SECONDS (FILLS SCREEN)
DECIMAL / HEX.
КИ 570” кеше;
6 connectors, 9 chips, sockets
and other parts.
*Add $3 for ship & hndl. m
Calif. res add 6% tax. i om
To order send check or M.O. to: *
( ompute
301 16th Ave
San Francisco, CA 94118
MORE: Plans, Kits,
Programs. Inquire.
ontinuum
(415) 752 6294
$15.00 FOR BOTH PROGRAMS
POSTPAID
BOB BERCH
19 JAQUES ST.
ROCHESTER, N.Y.
14620
Ed. -А WORD OF CAUTION: Any
hardware project for your computer must
be approached with extreme caution.
SYNC cannot be responsible for any
problem that may arise from attempting
hardware projects. Obviously, any dam-
age to your computer can be costly in
time and money.
Пг rss —
Thick Black Bars
George R. Ingle
In SYNC 1:6 Cecil Bridges points out
that the thick black bars on the display
may be caused by a failing capacitor in
the power supply. However, it is not
necessary to crack open the mains power
adapter to replace the 1000uF capacitor.
A simpler solution is to add another
capacitor, rated 200-470uF at 25wv, across
the +5у and ground connection to the
UHF/VHF modulator. This not only
corrects the leaking capacitor problem
but also greatly reduces the "lining" of
the display caused by the ZX80 display
circuit itself. Obviously, a miniature
capacitor should be used because of the
minimal free space inside the computer
case.
Comp.
Video
VHF/UHF
Modulator
e cH
200-470uF =
Insufficient
Filtering Solved
Robert D. Hartung
Like many others I found that the DC
filtering capacitance of the power supply
included with the 16K RAM pack is
borderline in supporting the demands of
both the RAM pack and the ZX80 with
its 17 extra ICs as compared with the
ZX81. The symptoms of insufficient fil-
tering include false LOADs from the
excessive 60 Hz ripple in the DC and a
horizontal line or blank bar moving verti-
cally through the TV display every two
seconds. If these symptoms disappear
when the RAM pack is disconnected,
either some component is drawing exces-
sive current or, more likely, the added
load of the RAM pack is causing inade-
quate filtering of the unregulated DC
power to the computer.
Memory Expansion Power Supply
George В. Ingle
David Sommers mentions (SYNC 1:6)
the problem of using an additional power
supply with his memory expansion. For
those building an additional memory
expansion unit, the following suggestions
might be helpful.
1) Insure that all components are using
а common ground return.
2) Do not connect the +5v regulated
voltages or +9 to +12 unregulated volt-
age in parallel. Instead, use a common
ground whether earth or floating,
depending on the design, and feed the
additional memory unit with a separate
+ 5v regulated supply.
3) Insure that the additional power
supply is well-filtered and uses, if possible,
a three prong grounded outlet and AC
supply cord.
(Ed.—A schematic of the author's power
supply that provides for + 15v reg., +12v
гер., +5у reg., and -12v unreg. is available
from the author for $1.00 and a SASE.)
George R. Ingle, 24593 1/2 Monterey Ave., San Bernadino, CA 92410.
74
Adding a 2200uF 50VDC capacitor
across the output wires near the power
jack eliminates the problem. Use a VOM
or an LED tester to determine which is
the positive output wire and which is the
negative in order to be sure that you are
observing the proper polarity in con-
necting the capacitor. This capacitor also
gives some protection against momentary
drop-outs occurring on the main power
lines.
A note of caution: since a capacitor of
this size stores considerable energy even
after the power pack is unplugged from
the AC outlet, I strongly recommend
inserting a small lever type microswitch
(e.g., Radio Shack 275-016) in one of the
DC wires near the computer power plug.
This will avoid possible burning or fusing
of the power jack outlets when the plug is
inserted or withdrawn when the capacitor
is charged. The switch gives a bonus of
being a "panic" switch to get out of
endless program sequences as well as to
cut the power off when connecting or
disconnecting the 16K RAM pack.
To install the switch, cut and strip one
of the power cord wires as near to the
computer plug as practicable. Solder one
wire end to the C lug of the switch and
the other to the NC lug (normally closed).
An LED pilot light can be added at the
same time. Strip, but do not cut, one-half
inch of the other power cord wire. Again,
determine the polarity of this wire with
the wire which goes from the switch lug
to the computer plug. Solder the LED
lead which is nearest the flatted side of
the LED base (cathode) to the negative
wire. Solder a IK resistor to the other
LED lead and in series to the wire which
is positive. Carefully tape all bare leads
and connections to isolate them from
each other. Since only 45 grams of pres-
sure will open the switch, taping it to the
power cord and plug will give all the
necessary support.
Robert D. Hartung, PO Box 125, Palmyra, NY
14522.
SYNC Magazine
USE OUR PLANS AND SAVE $$$$$
ФЕ YOUR SINCLAIR
KEYBOARD how to add a full-size keyboard
to a ZX/80 or 81.Includes instructions on how
to use any extra keys for Shift Lock, Automatic
shift, Automatic Repeat, and Reset. $5.00
POWER SUPPLY Running a little hot? Design
and build your own supply to fit your needs
at a fraction of wired price. Includes how to
estimate both present and future needs and
covers both single and multi-voltage. $5.00
BUSS Inexpensive exspansion system unlimits
your edge connector. $3.5
JOYSTICK Add popular. Atari joysticks and
find out how much fun games can be. $2.50
Send check or money order to:
SYNCHRONIZE
Box 1667
Kerrville, Texas 78028
Sinclair ® Computer Owners
| vou NEED THIS!
* Protects against power line glitches
* Provides extra power for add-ons
* Cuts heat in the internal regulator
The HL-1205 uses the same modern switching regulator technology
as used on big computers to trade harmful heat for extra power.
so ... dust plug your ZX81 A.C. Adapter into the HL-1205, plug
the HL-1205 into the computer and turn on the switch. Add a
rechargable 12 volt battery (not supplied) to have an UNINTER-
RUPTABLE POWER SUPPLY, or operate from 12V car or truck
system. А MUST FOR SERIOUS COMPUTER USERS
To order send check to:
Hurricane Electronics Lab
P.O. BOX 1280
HURRICANE, UTAH 84737
[801]635-2003
$35.95 plus $4.00
shipping and handling
30 day money back guarantee
————:, IDEO One а
PRACTICAL 73:81 SOFTWARE
1X 81-4 Not Just
For Games
Anymore!
Z2X-PANDING, LTD., an American campany, uses the tremen-
dous 2i-81 Tm data handling capabilities to make our daily
tasks easier. Programs are on cassette, thoroughly tested,
ith easy-to-read printed instructions, written in BASIC to
allow tailoring to your special needs. Send a STAMPED SELF-
ADDRESSED ENVELOPE for details on these and other pro
1. YOUR SPECIAL DAY--1K—Good example of using
succesSive equations to answer a practical question.
Enter any date in history,and ZX-Sly, will tell you the
Gay of the week on which it occurred. Useful in many
fields and a great ZX-8lp, demonstration. . ONLY $3.75%
2. CLOCKS AND TIMERS--1K—A digital clock(stan-
dard or military time), a count-up timer (for telephone |
calls), and a count-down timer (useful in cooking). An-
other great ZX-8lt, demonstration. . . . . ONLY 33.75*
3. ANYPOINT РІОТТЕВ--1К--Сгипсһев any data to
allow graphing any positive data points: stock prices,
temperature, experimental data, ес... . ONLY $3.75*
Le CHECKBOOK, INCOME TAX AND: BUDGET ORGANIZER--16K
А powerful yet easy to use finance program—10 jobs in menu
driven format. Checks and deposits are totaled and itemized
under desired categories for budget planning and income tax |
preparation. Makes checkbook balancing easy. Ninety trans- №
actions manipulated at one time with 16K. . . . ONLY #13.75%
XALL orders please add $1.25
ALL 3 FOR ONLY $8.7
ZX-PANDING,LTD. te total order to om POST-
PO. BOX 25 orders add $2.00 о iov aie
NEWTON, NC 28658 | созув. Your Me сы
in a U. 5. dollar draft pey- §
able to U. S. bank.)
704-464-2742
MUSIC and KALEIDOSCOPES
VIRTUOSO. A music synthesis program for the
Timex/Sinclair and ZX81 with 2K or more. NO
MUSIC KNOWLEDGE NECESSARY! 96 notes.
range from put put to above treble clef, any tempo.
Whole to 32nd notes. Songs may be saved for
future use. Required hardware? - - Your cassette
recorder. $6.95 pp.
PLAYER ZX81. A less versatile music program for
1K memory. Music instruction not included. $6.95
pp.
SQUARES and CROSSES, Kaleidoscopic
simulations for the same machines. 1K or more.
$6.95 pp.
All on standard cassette. Guaranteed to load.
Music programs include random sound listing or
save copy. Add $3.00 each, outside U.S.
Mail order only.:
William Don Maples
688 Moore St.
Lakewood, CO 80215.
Ear Input Circuit
James Dowell
I upgraded my ZX80 (UHF) with the
8K ROM and MicroAce Video Upgrade
kit. I had no loading problems while I was
using a Sears tape recorder. Later |
procured a Craig tape recorder as a
dedicated component of my system. Then
my loading problems began with no
apparent permanent solution.
Upon inspection of a defunct ZX80
(VHF) with supposed loading problems, I
discovered that Sinclair had made two
minor modifications to the ear input
circuit. One was the addition of a .01тї
capacitor across the terminals of the input
jack (RFI filter). Removal of this capac-
itor restored the loading capability of this
unit. The other modification was the
addition of a 6.8K resistor from the
connecting bus between C12 and R1 to
the +5V bus. Installing a similar resistor
in my original ZX80 cleared all of my
loading problems and greatly increased
the dynamic range of the input circuit.
Top Line Hook Solution
James Dowell
Tom Keeney’s fine article (SYNC 2:1)
points to a problem with the MicroAce
Video Upgrade kit and the top line. A
solution to this “top line hook” in SLOW
mode is as follows:
Connect a capacitor (.027-.030mf) from
pins 10-11 of IC6 to ground. Using the
space of the unused C9, insulate the “hot”
lead of the capacitor and pass it through
the +5V hole for C9 (next to pin 14 of
IC6) and connect to pins 10-11 of 1С6.
Connect the ground lead of the capacitor
to the ground hole for C9. Too little
capacitance will not quite correct the
hook whereas too much capacitance will
over-correct the hook.
I made a large cutout in the top cover
of the ZX80 and cemented a 4x6x3/4f
inch plastic box over the opening. This
gave me room to mount the Video
Upgrade, Keyboard Beeper, Video
Reverse Switch, and a Reset Switch in
the ZX80.
Although my ZxX80 with Video
Upgrade works fine with a ‘defective’ 8K
ROM, I have been unable to make it
work with the replacement ROM (which
works fine in a non-upgraded ZX80).
James Dowell, 735 Myra Ave., Chula Vista, CA
92010.
76
Problems in ROM Changing
Herb Hornung
A common problem which occurs when
replacing the 4K ROM with the 8K ROM
is that the computer does not turn on
every time (or even at all) when it is
plugged in. If you have this problem, you
can solve it by soldering a 33pf capacitor
from REFRESH to ground. That is, solder
Figure 1.
Expansion connector
Component side
the capacitor from pin 23A of the expan-
sion connector to the ground connection
of the RF modulator (case). Keep the
leads as short as possible (see Figure 1).
After performing this modification, I
checked to see if the 16K RAM pack still
worked and it did.
Pin 23A (RFSH)
RF
Modulator
7
Solder 33pf
capacitor here
Strong Signals оп KBD O through KBD 4
Herb Hornung
Quite a few ZX8ls that I have seen
have very strong signals on KBD 0
through KBD 4. This can cause the
following problems: 1) some shifted func-
tions will not work; 2) some characters
are always shifted; 3) some characters
will not print at all. These problems may
appear all the time or only after adding a
printer, plugging in a 16K memory mod-
ule, or upgrading the keyboard.
This condition can be corrected by
removing the 10K (2 resistor pack (RP3)
and replacing it with 8.2K Q resistors.
Solder one lead from each resistor to the
KBD 0 through KBD 4 a solder the other
leads together and to the “C” contact of
the circuit board (see Figure 2). In some
extreme cases it may be necessary to
change the resistor to as low as 6.8K (2.
Ed. — Herb Hornung is interested in hear-
ing from readers who have hardware
problems or information. He will attempt
to help (no charge) if a stamped, self-
addressed envelope is enclosed.
Figure 2.
C
Connect resistors
together as shown
RP)-—-[ 2 x
CIIIIIID ши
5 Pin keyboard 8 Pin keyboard
connector connector
Remove RP3 and replace
with 8.2K Q resistors
Herb Hornung, Double H Electronics, 195 Lelani, San Antonio, TX 78242.
SYNC Magazine
MOLDED OF STURDY,.:BEIGE ABS, THE ZC
ORGANIZER CONCEALS ALL THE ZX81 AND
CASSETTE RECORDER CABLES, YET YOUR
COMPUTER AND RECORDER ARE READY FOR
INSTANT ВЕ SPACE.IS ALSO-PROVIDED
FOR ADD ON MEMORIES SUCH AS THE 16K
SINCLAIR, OR 64K MEMOTEK.
GIVE YOUR ZX81 IT'S OWN HOME -
JUST $14.95 * $2 SHIPPING/HANDLING
SEND CHECK OR MONEY ORDER TO:
RUSKRAFT ENGINEERING
P.0. BOX 306, DEPT. A
TINLEY PARK, IL.60477
PLEASE ALLOW 4 TO 6 WEEKS FOR DEL.
Does your ZX-80 need a
home of its own?
Designed especially
for the Home
Computer. This
desk creates
organization
for all your
hardware and
software items.
Rich Wood
Grain Look
WALSH
| nO nf
ZEATING
SHIPPED
UNASSEMBLED,
CLIPS TOGETHER |
Мате
5 1 4. 95 | Address
SHIPPED U.P.S. | |
FRT.cOLLECT pO oy oe “р
DESK PRICE...$74.95 ОМАЗТЕВСАВО CIVISA
Over-All Size
24d x 331^ w x 33h
Apt. #
MAIL ORDER TO: (CHECK OR MONEY ORDER ENCLOSED CAM. EXP.
WALSH & Acct. #
SIMMONS INC. | Interbank # for Master сага: O11]
2511 lowa St.
St. Louis, MO ge] Exp. Date:
Signature:
practical
software
FOR THE SINCLAIR ZX80/81 (8K/16K)
2 Unique computer programs on cassette
e ZX INVENTORY e ZX DIRECTORY
e STORAGE OF 200 ITEMS AND PRICESe SORTS FILES ALPHABETICALLY
e PRINTING CAPABILITY (ZX81) e STORAGE OF 60 FILES (16K)
e COMPREHENSIVE SEARCH e PRINTING CAPABILITY (ZX81)
ROUTINES e COMPREHENSIVE SEARCH
ROUTINE
BOTH PROGRAMS EASILY MODIFIED TO
STORE MORE FILES WITH LARGER RAM PACK.
ONLY 19.95 EA.
BOTH PROGRAMS FOR 34.95
SEND CHECK OR MONEY ORDER TO:
SERVITRONICS
P.O. BOX 2024, HARTFORD, CONN. 06145
FOR INFORMATION OR VISA OR MASTERCARD ORDERS
CALL (203) 643-7900 SHIPPING U.S. $1.50 OUTSIDE U.S. $3.00
The Gateway Guide to the
ZX81 and ZX80
by Mark Charlton
The Gateway Guide is a practical programming man-
ual for the beginner that furnishes over 70 fully docu-
mented programs. The majority of the programs have
been written for easy conversion from machine to
machine (ZX81, 4K ZX80 or 1K 2Х80). un
The Gateway Guide describes each 4 |
function and statement, illustrates it
with a demonstration routine or pro-
gram, and combines it with previously
discussed material to provide a solid
basis for understanding your computer. `
5 V2" x 8", 172 pages. $8.95
--------------
Dept. 0000, 39 East Hanover Ave., Morris Plains, NJ 07950
ї Please send The Gateway Guide to the ZX81 апа ZX80 @ $8.95* each
1 plus $2.00 postage and handling. Outside U.S.A. add $3.00 рег order—
shipped air mail only.
i []Enclosedis$ д . ..*NgJresidents add 5% sales tax. i
| С Charge: O American Express О Visa O MasterCard i
| Account. = d
Eouneue-. ee
ДРЕ d S locos coL c аа Pie нн 0 аа а |
i
я Creative Computing Press \
i
j
Exp. Date
Addre
City/State/Zip
2720
CHARGE ORDERS-for your convenience phone
Toll Free 800-631-8112, In N.J. only (201) 540-0445.
ded dat a iss oom in abusu TEN
[2SOuUrces
The “Resources” column lists new
products for Sinclair users. Suppliers and
users are invited to send brief product
descriptions and ordering details to:
Resources, SYNC, 39 E. Hanover Ауе.,
Morris Plains, NJ 07950.
User Groups
e North Alabama ZX80/1
Group. For details contact:
Bob Boyer
1103 Rivlin Rd.
Huntsville, AL
(205) 883-4354 (evenings)
Users
% бап Francisco Bay Area Sinclair ZX
Users Group (ZUG). Publishes news-
letter SincLink. For details contact:
Paul D. Perreault
c/o Stanford Telecommunications,
Inc.
1195 Bordeaux Dr.
Sunnyvale, CA 94086
(418) 734-5300, x267
* Westinghouse ZX80/1 Users Club.
Newsletter. $1 contribution appreci-
ated. For details contact:
Jack Fogarty
Westinghouse MS 3525
PO Box 1521
Baltimore, MD 21203
. Pittsburgh Area Computer Club
(Special Interest Group: Sinclair). For
details contact:
Dick Walsh
1605 Middlecrest Dr.
Glenshaw, PA 15116
(412) 487-0789
e Chattanooga Area Sinclair Users. For
details contact:
Dan Williams
PO Box 1321
Collegedale, TN 37315
Forming a User Group
е Any Evanston, IL, area users inter-
ested in forming a group? Contact:
Brendan P. Holly
1246 Elmwood Ave.
Evanston, IL
78
ROM Disassembly
Sinclair ZX81 ROM Disassembly.
Part A (the operating system) by Dr.
Ian Logan, $15.00. Sinclair ZX81 ROM
Disassembly, Part B (calculator rou-
tines), $17.00. Sent direct by airmail
by the author. U.S. personal checks
accepted. Spectrum books in develop-
ment.
Logan Software (Lincoln)
24 Nurses Lane, Skellingthorpe
Lincoln LN6 OTT
United Kingdom
The ZX80 1K Disassembler for the
АК ROM ZX80 and The 2Х81 IK
Disassembler for the ZX81 and 8K
ROM ZX80. Begins with starting
address, a key is calculated and dis-
played, manual then gives mnemonic,
all numbers displayed in decimal,
about 100 bytes of RAM to store MC
program for disassembly; RAM mem-
ory test provided; addresses of bytes
failing the test are displayed. Manual,
reference cards, and cassette with
disassembler and memory test pro-
grams. $9.95 pp. for either 4K or 8K.
Further information and catalog upon
request. |
Lamo-Lem Laboratories
Box 2382
La Jolla, CA 92038-2382
ZXBUG V3.125. Machine code mon-
itor/debugger with full ZILOG dis-
assembler. Just under 4K; resides at
top of the 16K ZX81; 30 commands.
Allows: search of any block for any
occurrence of a byte or word, display
and altering of main and auxiliary
registers, examination of flags, replace-
ment in a given block of all occur-
rences of a byte with another, moving
blocks around in memory, display of
Z80 ZILOG Mnemonic disassembler
page by page. £7.00.
Artic Computing Ltd.
396 James Reckitt Ave.
Hull, North Humberside
United Kingdom
Catalogs/Directories/
Indexes/
e Software Vendor Directory. (6th ed.).
Cross referenced index covering 22
systems and over 12,000 software pro-
ducts in 300 categories obtainable from
1,800 software vendors and 123 hard-
ware vendors. $57.95; with 2 updates
in 12 months: $100 or $260 on disk.
Contact:
Micro-Software Services, Inc.
PO Box 482
Nyack,NY 10960
(914) 358-1340
е 2Х80/81 Users’ Library. A catalog
in 3-ring binder format with program-
ming tips and abstracts of programs
submitted by subscribers and checked
by library staff for accuracy and use-
fulness. Periodic newsletter. Program
prices: $1.50 for IK, $3.00 for 16K.
Annual subscription: $25 for U.S.; $32
for non-U.S. For further details con-
tact:
ZX80/81 Users’ Library
Suite 434
4614 Kilauea Ave.
Honolulu, HI 96816
Periodicals
e Imprint Software review program. А
quarterly newsletter of software
reviews by category. For details con-
tact:
Software Review
Imprint Software
420 South Howes
Ft. Collins, CO 80521
(303) 482-5574; Telex 45-4590
In U.K.:
Software Review
Imprint Software
16 Milton Ave.
Highgate, London N6
e ETC: Educational Technology and
Communication. A monthly newsletter
to help schools, esp. decision makers,
to move into the new technology. $36
for one year; $60 for two years.
ETC Subscription Department
Far West Laboratory
1855 Folsom St.
San Francisco, CA 94103
SYNC Magazine
Programming Programs
PEEK displays 100 memory locations
in decimal (Basic); BASE gives con-
versions of octal, decimal, binary, hex,
hibyte/lobyte (Basic); PPU a PEEK
and POKE Utility, a fully documented
monitor (Basic and mc). АП four рго-
grams on standard cassette and full
documentation (64 pp.; 8 1/2 x 11) for
$24.17. Bidirectional Dictionary gives
2 lists: from Decimal OP CODE
arranged numerically to Assembler
Mnemonic and from Assembler Mne-
monic arranged alpha-numerically to
Decimal OP CODE.
Joseph L. Hartmann
101 Tonnele Ave.
Jersey City, NJ 07306
Educational Programs
“Рип to Learn” series. 8 cassettes:
English Literature I and II, Geography,
History, Mathematics, Inventions, and
Music. $12.95 per cassette. $1.95 s&h
per order.
Sinclair Research Ltd.
3 Sinclair Plaza
Nashua, NH 03061
Business/Household
Vu-Calc constructs large tables for
purposes such as budgets, finances,
and projections ($14.95). Vu-File stor-
age and retrieval for collections,
accounts, directories, membership lists
($14.95). The Collectors Pack holds
up to 400 records in each of 6 cate-
gories ($17.95). The Club Record Con-
troller holds names, addresses, phone
numbers, and 5 additional categories
for up to 100 members on one cassette
($17.95). $1.95 s&h per order.
Sinclair Research Ltd.
3 Sinlair Plaza
Nashua, NH 03061
ZX681 Personal Banking System.
Keep detailed records of your
finances; uses unique machine code to
store all transactions in datafiles on
cassette separate from the program.
Cassette and 12 page manual for $20.
Large SAE for details.
J. P. Gibbons A.I.B.
14 Avalon Road |
Orpington, Kent, BR6 9AX
United Kingdom
July/August 1982
Check Register, Inventory, and more
programs for the ZX81 (16K to 64K).
Makes full use of the 64K. Can be user
defined to your RAM size. On high
energy cassette $9.95 plus $1.00 s&h.
Brittanysoft, Ltd.
PO Box 1043 |
Twin Falls, ID 83301
(208) 324-3086
Coin Collection, Stamp Collection,
and Baseball Card Collection. Data-
base inventory programs using menu
and descriptive prompts for ZX81 and
ZX80 or MicroAce with 8K ROM. 16K
RAM. Cassette (guaranteed loading)
and manual. Each title $4.95 plus $1.05
s&h. SASE for free catalog.
M. C. Hoffman
PO Box 117
Oakland, NJ 07436
Graphics Programs
GRAPHIX. Image processor. No
more tedious number punching to
"draw" on the screen. Features: trans-
ferable images, image mixer, image
reverser, up to 12 "files." ZX81/ZX80
(SK ROM); 16K RAM. $5.99 incl. post-
age.
Nick Godwin
4 Hurkur Crescent, Eyemouth,
Berwickshire TD14 5AP
Scotland
The Artist creates drawings and
paintings on the screen. Features:
users choice of brushes and back-
grounds, free mixing of graphics and
alphanumerics, easy specification of
lines and circles, ability to store com-
plex patterns and reproduce them
anywhere on the screen. Cassette and
instructions for $10.
KSOFT
845 Wellner Rd.
Naperville, IL 60540
RAM Expansion
EconoTech 16K RAM Pack. Uses
NMOS dynamic RAMs, standard 4116
memory chips, and Sinclair power
pack. Tight-fitting 44-way edge con-
nector with gold-plated contacts plugs
into expansion port; designed to pre-
vent wobble. Compatible with ZX
Printer. RAM pack with 6-month guar-
antee and comprehensive instructions
£19.95 (including VAT) plus £1.50 s&h
to anywhere in the world. For further
details contact:
EconoTech
30 Brockenhurst Way
London SW16 4UD
United Kingdom
2K RAM kit for ZX81 users with 1K
RAM. Increases program size (with
filled screen) by more than 10 times.
Kit includes: 2K-byte IC, 2 part socket,
jumper, solder, and easy instructions.
$29.95 postpaid.
Micro Logic Corp.
PO Box 174-ZB
Hackensack, NJ 07602
(201) 342-6518
Light Pen
Light pen for ZX81 users. Palm-sized
plug-on module with three modes:
DRAW, ERASE, and CLEAR. Allows
entering complex graphics by just
touching the screen. Upper 90% of
screen is free for graphics; lower
portion divided into three zones for
changing modes. Virtually eliminates
the PRINT and PLOT statements.
Images held in strings to be stored on
cassette if desired. $69.95.
ZODEX
East Hill
Oakham, MA 02068
Interference Control
Toll Free Interference Control Hot
Line. Experienced staff will analyze
problem situations and make specific
recommendations for control of pro-
cessor or peripheral interference. Hot
line: 1-800-225-4876 between 9 a.m.
and 4 p.m. Eastern Time Monday
through Friday. Free 40 page Inter-
ference Control Product Catalog.
Electronic Specialists, Inc.
171 S. Main St.
PO Box 389
Natick, MA 01760
(617) 655-1532
Fairs and Workshops
MICROSCENE BRUM 82. A big
ZX80/ZX81/Spectrum show in the
center of Britain’s second city: Bingley
Hall, Birmingham 1 on 11 September,
1982. Advance tickets £1; advance
brochures £1. Send to:
Microscene
6 Battenhall Road
Harborne
Birmingham B17 9UD
United Kingdom
Games
Backgammon ($9.95), Chess ($12.95),
Fantasy Games ($8.95), Space Raiders
and Bombers ($8.95), Flight Simulation
($9.95), 8 different Super Program
cassettes ($8.95 ea.). $1.95 s&h per
order.
Sinclair Research Ltd.
3 Sinclair Plaza
Nashua, NH 03061 2"
79
50 МЕТҮІК |
PROGRAMS FOR
THE 2Х81
WIDE ASSORTMENT OF
ACTIVITIES, GAMES, UTILITY
PROGRAMS, ETC.
MANY WITH GRAPHICS
$9.95 INCLUDES
POSTAGE/HANDLING
LEE CARTER
BOX 246
HARHISON, ME..
04040
n2
16K INSIDE?!!
No Bulky Add-ons!
Leaves back connector free
for printer or peripherals!
Inexpensive using your parts.
Can be assembled and installed by
anyone who can use a soldering pen.
Complete instructions, including
schematic, parts list, suggested
Board layout, assembly and instal-
lation. $7.95
With optional pre-made P.C. Board.
$18.95 from:
Independence Research
P.O. Box 1497
Orem, Utah 84057
Index to Advertisers
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EZRA GROUP II
EZRA GROUP II
The 2Х81/80/Т5-1000 5 are making а name
with LOW prices...
WE CHALLENGE THE SOFTWARE COMPANIES
TO LOWER THEIR PRICES!
For TS-1000/ZX81/ZX80/8K ROM
1K and 16K RAM versions
Biorhythms. . re ee ere 1.00
Graphics Billboard езен ea ар на бек baad eu sae оны иншаны 1.00
Horse Басе......................................... 1.00
SPINNER Т.М. (like Rubik's) 16Қ....................2.00
Skew-a-Sketch (like Еїсһ)............................ 1.00
Improved Pause (7Х81).............................. 1.00
Linear Вепгевбіоп................................... 2.00
CHEWTER T.M. (Like Pac M-N) SLOW .................. 2.95
Shootist. асаана RR RT RR RR ES 2.00
Random MUSIC! SLOW ............................... 2.00
Self Addressed Stamped Envelope
Gets YOU our Goodies Catalog
ALL ORDERS AND CATALOG REQUESTS GET FREE
Galactic Messages PROGRAM.
EZRA GROUP II
EZRA GROUP II
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